Method and apparatus for transmitting or receiving signal in wireless communication system

ABSTRACT

A method and an apparatus for receiving a signal by a terminal in a wireless communication system according to an embodiment of the present invention comprises the steps of: establishing an RNTI associated with an MCS by a terminal; receiving a control channel for scheduling transmission of an uplink data channel or reception of a downlink data channel; and transmitting the uplink data channel or receiving the downlink data channel on the basis of one MCS table of a plurality of MCS tables, wherein the uplink data channel or the downlink data channel has been scheduled by the control channel and the one MCS table is determined on the basis of an RNTI associated with the MCS and an RNTI associated with the control channel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/646,453, filed on Mar. 11, 2020, which is a National Stageapplication under 35 U.S.C. § 371 of International Application No.PCT/KR2019/001833, filed on Feb. 14, 2019, which claims the benefit ofU.S. Provisional Application No. 62/688,987, filed on Jun. 22, 2018,Korean Application No. 10-2018-0054412, filed on May 11, 2018, U.S.Provisional Application No. 62/634,185, filed on Feb. 22, 2018, and U.S.Provisional Application No. 62/630,264, filed on Feb. 14, 2018. Thedisclosures of the prior applications are incorporated by reference intheir entirety.

TECHNICAL FIELD

The present disclosure relates to a wireless communication system, andmore particularly, to a method and apparatus for transmitting andreceiving a signal.

BACKGROUND

Wireless access systems have been widely deployed to provide varioustypes of communication services such as voice or data. In general, awireless access system is a multiple access system that supportscommunication of multiple users by sharing available system resources (abandwidth, transmission power, etc.) among them. For example, multipleaccess systems include a code division multiple access (CDMA) system, afrequency division multiple access (FDMA) system, a time divisionmultiple access (TDMA) system, an orthogonal frequency division multipleaccess (OFDMA) system, and a single carrier frequency division multipleaccess (SC-FDMA) system.

The latency of packet data is one of important performance metrics. Toreduce the latency of packet data and provide faster Internet access toan ender user is one of challenging issues in designing thenext-generation mobile communication system called new radio accesstechnology (RAT) as well as long term evolution (LTE).

The present disclosure provides a description related to a referencesignal in a wireless communication system supporting a reduction inlatency.

SUMMARY

An aspect of the present disclosure is to provide a method and apparatusfor efficiently reporting a user equipment (UE) state and receiving adownlink signal or transmitting an uplink signal by a UE in a wirelesscommunication system.

It will be appreciated by persons skilled in the art that the objectsthat could be achieved with the present disclosure are not limited towhat has been particularly described hereinabove and the above and otherobjects that the present disclosure could achieve will be more clearlyunderstood from the following detailed description.

The present disclosure provides a method and apparatus for transmittingand receiving a signal in a wireless communication system.

In an aspect of the present disclosure, a method of transmitting andreceiving a signal, performed by a user equipment (UE) in a wirelesscommunication system includes configuring a radio network temporaryidentity (RNTI) related to a modulation and coding scheme (MCS),receiving a control channel for scheduling transmission of an uplinkdata channel or reception of a downlink data channel, and transmittingthe uplink data channel or receiving the downlink data channel based onone of a plurality of MCS tables, the uplink data channel or thedownlink data channel being scheduled by the control channel. The one ofthe plurality of MCS tables is determined based on the RNTI related tothe MCS and an RNTI related to the control channel.

In another aspect of the present disclosure, a UE for transmitting andreceiving a signal, performed in a wireless communication systemincludes a transceiver and a processor configured to control thetransceiver. The processor is configured to configure an RNTI related toan MCS, receive a control channel for scheduling transmission of anuplink data channel or reception of a downlink data channel bycontrolling the transceiver, and transmit the uplink data channel orreceive the downlink data channel based on one of a plurality of MCStables by controlling the transceiver, the uplink data channel or thedownlink data channel being scheduled by the control channel. The one ofthe plurality of MCS tables is determined based on the RNTI related tothe MCS and an RNTI related to the control channel.

In the method or apparatus, the one of the plurality of MCS tables maybe determined based on information for a quadrature amplitude modulation(QAM) related to an MCS table to be used for the UE, received byhigher-layer signaling.

In the method or apparatus, the RNTI related to the MCS may be anMCS-cell-RNTI (MCS-C-RNTI), and the one of the plurality of MCS tablesmay be determined based on the RNTI related to the control channel beingthe MCS-C-RNTI and the information for a QAM related to an MCS table tobe used for the UE being for 256QAM or 64QAM or less.

In the method or apparatus, the UE may determine a modulation order anda target code rate to be used for reception of a physical downlinkshared channel (PDSCH) based on an MCS field included in the controlchannel and the one of the plurality of MCS tables.

In the method or apparatus, the RNTI related to the control channel maybe determined based on a block error rate (BLER).

In the method or apparatus, the one of the plurality of MCS tables maybe determined in further consideration of at least one of a downlinkcontrol information (DCI) format of the control channel and/or furtherbased on semi-persistent scheduling being configured for the uplink datachannel or the downlink data channel.

In the method or apparatus, the UE may transmit UE capabilityinformation to a network. The UE capability information may includeinformation for the number of updatable channel state information (CSI)processes for each combination of downlink and uplink transmission timeinterval (TTI) lengths.

In the method or apparatus, the information for the number of updatableCSI processes for each combination of downlink and uplink TTI lengthsmay include first information for the number of CSI processes based onthe combination of downlink and uplink TTI lengths being a slot and aslot,

second information for the number of CSI processes based on thecombination of downlink and uplink TTI lengths being a subslot and aslot, third information for the number of CSI processes based on thecombination of downlink and uplink TTI lengths being a subslot and asubslot and a first processing time being configured, and fourthinformation for the number of CSI processes based on the combination ofdownlink and uplink TTI lengths being a subslot and a subslot and asecond processing time being configured.

It will be understood by those skilled in the art that theabove-described aspects of the present disclosure are merely part of theembodiments of the present disclosure and various modifications andalternatives could be developed from the following technical features ofthe present disclosure.

According to an embodiment of the present disclosure, a user equipment(UE) state may be efficiently reported in consideration of a requirementfor each channel, and a downlink signal may be received or an uplinksignal may be transmitted accordingly.

It will be appreciated by persons skilled in the art that the effectsthat can be achieved with the present disclosure are not limited to whathas been particularly described hereinabove and other advantages of thepresent disclosure will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are diagrams for an example of a radio frame structureused in wireless communication system;

FIG. 2 is a diagram for an example of a downlink (DL)/uplink (UL) slotstructure in a wireless communication system;

FIG. 3 is a diagram for an example of a DL subframe structure used in3GPP LTE/LTE-A system;

FIG. 4 is a diagram for an example of a UL subframe structure used in3GPP LTE/LTE-A system;

FIG. 5 illustrates a decrease in the length of a TTI according toreduction in user-plane latency;

FIG. 6 illustrates an example of configuring a plurality of short TTIsin one subframe;

FIGS. 7A to 7D illustrates the structures of DL subframes includingshort TTIs of multiple lengths (various numbers of symbols);

FIGS. 8A and 8B illustrate the structures of DL subframes includingshort TTIs of 2 and 3 symbols;

FIG. 9 is a diagram illustrating a self-contained subframe structureapplicable to the present disclosure;

FIG. 10 is a conceptual view illustrating a method according to anembodiment of the present disclosure; and

FIG. 11 is a block diagram showing an apparatus for embodyingembodiment(s) of the present disclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to the preferred embodiments of thepresent disclosure, examples of which are illustrated in theaccompanying drawings. The accompanying drawings illustrate exemplaryembodiments of the present disclosure and provide a more detaileddescription of the present disclosure. However, the scope of the presentdisclosure should not be limited thereto.

In some cases, to prevent the concept of the present disclosure frombeing ambiguous, structures and apparatuses of the known art will beomitted or will be shown in the form of a block diagram based on mainfunctions of each structure and apparatus. Also, wherever possible, thesame reference numbers will be used throughout the drawings and thespecification to refer to the same or like parts.

In the present disclosure, a user equipment (UE) is fixed or mobile. TheUE is a device that transmits and receives user data and/or controlinformation by communicating with a base station (BS). The term ‘UE’ maybe replaced with ‘terminal equipment’, ‘mobile station (MS)’, ‘mobileterminal (MT)’, ‘user terminal (UT)’, ‘subscriber station (SS)’,‘wireless device’, ‘personal digital assistant (PDA)’, ‘wireless modem’,‘handheld device’, etc. ABS is typically a fixed station thatcommunicates with a UE and/or another BS. The BS exchanges data andcontrol information with a UE and another BS. The term ‘BS’ may bereplaced with ‘advanced base station (ABS)’, ‘Node B’, ‘evolved-Node B(eNB)’, ‘base transceiver system (BTS)’, ‘access point (AP)’,‘processing server (PS)’, etc. In the following description, BS iscommonly called eNB.

In the present disclosure, a node refers to a fixed point capable oftransmitting/receiving a radio signal to/from a UE by communication withthe UE. Various eNBs may be used as nodes. For example, a node may be aBS, NB, eNB, pico-cell eNB (PeNB), home eNB (HeNB), relay, repeater,etc. Furthermore, a node may not be an eNB. For example, a node may be aradio remote head (RRH) or a radio remote unit (RRU). The RRH and RRUhave power levels lower than that of the eNB. Since the RRH or RRU(referred to as RRH/RRU hereinafter) is connected to an eNB through adedicated line such as an optical cable in general, cooperativecommunication according to RRH/RRU and eNB may be smoothly performedcompared to cooperative communication according to eNBs connectedthrough a wireless link. At least one antenna is installed per node. Anantenna may refer to an antenna port, a virtual antenna or an antennagroup. A node may also be called a point. Unlink a conventionalcentralized antenna system (CAS) (i.e. single node system) in whichantennas are concentrated in an eNB and controlled an eNB controller,plural nodes are spaced apart at a predetermined distance or longer in amulti-node system. The plural nodes may be managed by one or more eNBsor eNB controllers that control operations of the nodes or schedule datato be transmitted/received through the nodes. Each node may be connectedto an eNB or eNB controller managing the corresponding node via a cableor a dedicated line. In the multi-node system, the same cell identity(ID) or different cell IDs may be used for signal transmission/receptionthrough plural nodes. When plural nodes have the same cell ID, each ofthe plural nodes operates as an antenna group of a cell. If nodes havedifferent cell IDs in the multi-node system, the multi-node system maybe regarded as a multi-cell (e.g. macro-cell/femto-cell/pico-cell)system. When multiple cells respectively configured by plural nodes areoverlaid according to coverage, a network configured by multiple cellsis called a multi-tier network. The cell ID of the RRH/RRU may beidentical to or different from the cell ID of an eNB. When the RRH/RRUand eNB use different cell IDs, both the RRH/RRU and eNB operate asindependent eNBs.

In a multi-node system according to the present disclosure, which willbe described below, one or more eNBs or eNB controllers connected toplural nodes may control the plural nodes such that signals aresimultaneously transmitted to or received from a UE through some or allnodes. While there is a difference between multi-node systems accordingto the nature of each node and implementation form of each node,multi-node systems are discriminated from single node systems (e.g. CAS,conventional MIMO systems, conventional relay systems, conventionalrepeater systems, etc.) since a plurality of nodes providescommunication services to a UE in a predetermined time-frequencyresource. Accordingly, embodiments of the present disclosure withrespect to a method of performing coordinated data transmission usingsome or all nodes may be applied to various types of multi-node systems.For example, a node refers to an antenna group spaced apart from anothernode by a predetermined distance or more, in general. However,embodiments of the present disclosure, which will be described below,may even be applied to a case in which a node refers to an arbitraryantenna group irrespective of node interval. In the case of an eNBincluding an X-pole (cross polarized) antenna, for example, theembodiments of the preset disclosure are applicable on the assumptionthat the eNB controls a node composed of an H-pole antenna and a V-poleantenna.

A communication scheme through which signals are transmitted/receivedvia plural transmit (Tx)/receive (Rx) nodes, signals aretransmitted/received via at least one node selected from plural Tx/Rxnodes, or a node transmitting a downlink (DL) signal is discriminatedfrom a node transmitting an UL signal is called multi-eNB MIMO orcoordinated multi-point Tx/Rx (CoMP). Coordinated transmission schemesfrom among CoMP communication schemes may be categorized into jointprocessing (JP) and scheduling coordination. The former may be dividedinto joint transmission (JT)/joint reception (JR) and dynamic pointselection (DPS) and the latter may be divided into coordinatedscheduling (CS) and coordinated beamforming (CB). DPS may be calleddynamic cell selection (DCS). When JP is performed, more variouscommunication environments may be generated, compared to other CoMPschemes. JT refers to a communication scheme by which plural nodestransmit the same stream to a UE and JR refers to a communication schemeby which plural nodes receive the same stream from the UE. The UE/eNBcombine signals received from the plural nodes to restore the stream. Inthe case of JT/JR, signal transmission reliability may be improvedaccording to transmit diversity since the same stream is transmittedfrom/to plural nodes. DPS refers to a communication scheme by which asignal is transmitted/received through a node selected from plural nodesaccording to a specific rule. In the case of DPS, signal transmissionreliability may be improved because a node having a good channel statebetween the node and a UE is selected as a communication node.

In the present disclosure, a cell refers to a specific geographical areain which one or more nodes provide communication services. Accordingly,communication with a specific cell may mean communication with an eNB ora node providing communication services to the specific cell. A DL/ULsignal of a specific cell refers to a DL/UL signal from/to an eNB or anode providing communication services to the specific cell. A cellproviding UL/DL communication services to a UE is called a serving cell.Furthermore, channel status/quality of a specific cell refers to channelstatus/quality of a channel or a communication link generated between aneNB or a node providing communication services to the specific cell anda UE. In 3GPP LTE-A systems, a UE may measure DL channel state from aspecific node using one or more channel state information referencesignals (CSI-RSs) transmitted through antenna port(s) of the specificnode on a CSI-RS resource allocated to the specific node. In general,neighboring nodes transmit CSI-RS resources on orthogonal CSI-RSresources. When CSI-RS resources are orthogonal, this means that theCSI-RS resources have different subframe configurations and/or CSI-RSsequences which specify subframes to which CSI-RSs are allocatedaccording to CSI-RS resource configurations, subframe offsets andtransmission periods, etc. which specify symbols and subcarrierscarrying the CSI RSs.

In the present disclosure, physical DL control channel (PDCCH)/physicalcontrol format indicator channel (PCFICH)/physical hybrid automaticrepeat request indicator channel (PHICH)/physical DL shared channel(PDSCH) refer to a set of time-frequency resources or resource elements(Res) respectively carrying DL control information (DCI)/control formatindicator (CFI)/acknowledgement/negative acknowledgement (DLACK/NACK)/DL data. In addition, physical uplink control channel(PUCCH)/physical uplink shared channel (PUSCH)/physical random accesschannel (PRACH) refer to sets of time-frequency resources or REsrespectively carrying uplink control information (UCI)/UL data/randomaccess signals. In the present disclosure, a time-frequency resource oran RE, which is allocated to or belongs toPDCCH/PCFICH/PHICH/PDSCH/PUCCH/PUSCH/PRACH, is referred to as aPDCCH/PCFICH/PHICH/PDSCH/PUCCH/PUSCH/PRACH RE orPDCCH/PCFICH/PHICH/PDSCH/PUCCH/PUSCH/PRACH resource. In the followingdescription, transmission of PUCCH/PUSCH/PRACH by a UE is equivalent totransmission of UL control information/UL data/random access signalthrough or on PUCCH/PUSCH/PRACH. Furthermore, transmission ofPDCCH/PCFICH/PHICH/PDSCH by an eNB is equivalent to transmission of DLdata/control information through or on PDCCH/PCFICH/PHICH/PDSCH.

FIGS. 1A and 1B illustrate an exemplary radio frame structure used in awireless communication system. FIG. 1A illustrates a frame structure forfrequency division duplex (FDD) used in 3GPP LTE/LTE-A and FIG. 1Billustrates a frame structure for time division duplex (TDD) used in3GPP LTE/LTE-A.

Referring to FIGS. 1A and 1B, a radio frame used in 3GPP LTE/LTE-A has alength of 10 ms (307200 Ts) and includes 10 subframes in equal size. The10 subframes in the radio frame may be numbered. Here, Ts denotessampling time and is represented as Ts=1/(2048*15 kHz). Each subframehas a length of 1 ms and includes two slots. 20 slots in the radio framemay be sequentially numbered from 0 to 19. Each slot has a length of 0.5ms. A time for transmitting a subframe is defined as a transmission timeinterval (TTI). Time resources may be discriminated by a radio framenumber (or radio frame index), subframe number (or subframe index) and aslot number (or slot index).

The radio frame may be configured differently according to duplex mode.Downlink transmission is discriminated from UL transmission by frequencyin FDD mode, and thus the radio frame includes only one of a DL subframeand an UL subframe in a specific frequency band. In TDD mode, DLtransmission is discriminated from UL transmission by time, and thus theradio frame includes both a DL subframe and an UL subframe in a specificfrequency band.

Table 1 shows DL-UL configurations of subframes in a radio frame in theTDD mode.

TABLE 1 Downlink- Uplink- to-Uplink downlink Switch-point Subframenumber configuration periodicity 0 1 2 3 4 5 6 7 8 9 0  5 ms D S U U U DS U U U 1  5 ms D S U U D D S U U D 2  5 ms D S U D D D S U D D 3 10 msD S U U U D D D D D 4 10 ms D S U U D D D D D D 5 10 ms D S U D D D D DD D 6  5 ms D S U U U D S U U D

In Table 1, D denotes a DL subframe, U denotes an UL subframe and Sdenotes a special subframe. The special subframe includes three fieldsof DwPTS (Downlink Pilot Time Slot), GP (Guard Period), and UpPTS(Uplink Pilot Time Slot). DwPTS is a period reserved for DL transmissionand UpPTS is a period reserved for UL transmission. Table 2 showsspecial subframe configuration.

TABLE 2 Normal cyclic prefix in downlink UpPTS Extended cyclic prefix indownlink Special Normal Extended UpPTS subframe cyclic prefix cyclicprefix Normal cyclic Extended cyclic configuration DwPTS in uplink inuplink DwPTS prefix in uplink prefix in uplink 0  6592 · T_(s) 2192 ·T_(s) 2560 · T_(s)  7680 · T_(s) 2192 · T_(s) 2560 · T_(s) 1 19760 ·T_(s) 20480 · T_(s) 2 21952 · T_(s) 23040 · T_(s) 3 24144 · T_(s) 25600· T_(s) 4 26336 · T_(s)  7680 · T_(s) 4384 · T_(s) 5120 · T_(s) 5  6592· T_(s) 4384 · T_(s) 5120 · T_(s) 20480 · T_(s) 6 19760 · T_(s) 23040 ·T_(s) 7 21952 · T_(s) 12800 · T_(s) 8 24144 · T_(s) — — — 9 13108 ·T_(s) — — —

FIG. 2 illustrates an exemplary DL/UL slot structure in a wirelesscommunication system. Particularly, FIG. 2 illustrates a resource gridstructure in 3GPP LTE/LTE-A. A resource grid is present per antennaport.

Referring to FIG. 2 , a slot includes a plurality of OFDM (OrthogonalFrequency Division Multiplexing) symbols in the time domain and aplurality of resource blocks (RBs) in the frequency domain. An OFDMsymbol may refer to a symbol period. A signal transmitted in each slotmay be represented by a resource grid composed of N_(RB) ^(DL/UL)*N_(sc)^(RB) subcarriers and N_(symb) ^(DL/UL) OFDM symbols. Here, N_(RB) ^(DL)denotes the number of RBs in a DL slot and N_(RB) ^(UL) denotes thenumber of RBs in an UL slot. N_(RB) ^(DL) and N_(RB) ^(UL) respectivelydepend on a DL transmission bandwidth and a UL transmission bandwidth.N_(symb) ^(DL) denotes the number of OFDM symbols in the DL slot andN_(symb) ^(UL) denotes the number of OFDM symbols in the UL slot. Inaddition, N_(sc) ^(RB) denotes the number of subcarriers constructingone RB.

An OFDM symbol may be called an SC-FDM (Single Carrier FrequencyDivision Multiplexing) symbol according to multiple access scheme. Thenumber of OFDM symbols included in a slot may depend on a channelbandwidth and the length of a cyclic prefix (CP). For example, a slotincludes 7 OFDM symbols in the case of normal CP and 6 OFDM symbols inthe case of extended CP. While FIG. 2 illustrates a subframe in which aslot includes 7 OFDM symbols for convenience, embodiments of the presentdisclosure may be equally applied to subframes having different numbersof OFDM symbols. Referring to FIG. 2 , each OFDM symbol includes N_(RB)^(DL/UL)*N_(sc) ^(RB) subcarriers in the frequency domain. Subcarriertypes may be classified into a data subcarrier for data transmission, areference signal subcarrier for reference signal transmission, and nullsubcarriers for a guard band and a direct current (DC) component. Thenull subcarrier for a DC component is a subcarrier remaining unused andis mapped to a carrier frequency (f0) during OFDM signal generation orfrequency up-conversion. The carrier frequency is also called a centerfrequency.

An RB is defined by N_(symb) ^(DL/UL) (e.g. 7) consecutive OFDM symbolsin the time domain and N_(sc) ^(RB) (e.g. 12) consecutive subcarriers inthe frequency domain. For reference, a resource composed by an OFDMsymbol and a subcarrier is called an RE or a tone. Accordingly, an RB iscomposed of N_(symb) ^(DL/UL)*N_(sc) ^(RB) REs. Each RE in a resourcegrid may be uniquely defined by an index pair (k, l) in a slot. Here, kis an index in the range of 0 to N_(symb) ^(DL/UL)*N_(sc) ^(RB)−1 in thefrequency domain and l is an index in the range of 0 to N_(symb)^(DL/UL)−1.

Two RBs that occupy N_(sc) ^(RB) consecutive subcarriers in a subframeand respectively disposed in two slots of the subframe are called aphysical resource block (PRB) pair. Two RBs constituting a PRB pair havethe same PRB number (or PRB index). A virtual resource block (VRB) is alogical resource allocation unit for resource allocation. The VRB hasthe same size as that of the PRB. The VRB may be divided into alocalized VRB and a distributed VRB depending on a mapping scheme of VRBinto PRB. The localized VRBs are mapped into the PRBs, whereby VRBnumber (VRB index) corresponds to PRB number. That is, n_(PRB)=n_(VRB)is obtained. Numbers are given to the localized VRBs from 0 to N_(VRB)^(DL)−1, and N_(VRB) ^(DL)=N_(RB) ^(DL) is obtained. Accordingly,according to the localized mapping scheme, the VRBs having the same VRBnumber are mapped into the PRBs having the same PRB number at the firstslot and the second slot. On the other hand, the distributed VRBs aremapped into the PRBs through interleaving. Accordingly, the VRBs havingthe same VRB number may be mapped into the PRBs having different PRBnumbers at the first slot and the second slot. Two PRBs, which arerespectively located at two slots of the subframe and have the same VRBnumber, will be referred to as a pair of VRBs.

FIG. 3 illustrates a DL subframe structure used in 3GPP LTE/LTE-A.

Referring to FIG. 3 , a DL subframe is divided into a control region anda data region. A maximum of three (four) OFDM symbols located in a frontportion of a first slot within a subframe correspond to the controlregion to which a control channel is allocated. A resource regionavailable for PDCCH transmission in the DL subframe is referred to as aPDCCH region hereinafter. The remaining OFDM symbols correspond to thedata region to which a PDSCH is allocated. A resource region availablefor PDSCH transmission in the DL subframe is referred to as a PDSCHregion hereinafter. Examples of DL control channels used in 3GPP LTEinclude a PCFICH, a PDCCH, a PHICH, etc. The PCFICH is transmitted at afirst OFDM symbol of a subframe and carries information regarding thenumber of OFDM symbols used for transmission of control channels withinthe subframe. The PHICH is a response of UL transmission and carries anHARQ ACK/NACK signal.

Control information carried on the PDCCH is called DL controlinformation (DCI). The DCI contains resource allocation information andcontrol information for a UE or a UE group. For example, the DCIincludes a transport format and resource allocation information of a DLshared channel (DL-SCH), a transport format and resource allocationinformation of an UL shared channel (UL-SCH), paging information of apaging channel (PCH), system information on the DL-SCH, informationabout resource allocation of an upper layer control message such as arandom access response transmitted on the PDSCH, a transmit controlcommand set with respect to individual UEs in a UE group, a transmitpower control command, information on activation of a voice over IP(VoIP), DL assignment index (DAI), etc. The transport format andresource allocation information of the DL-SCH are also called DLscheduling information or a DL grant and the transport format andresource allocation information of the UL-SCH are also called ULscheduling information or a UL grant. The size and purpose of DCIcarried on a PDCCH depend on DCI format and the size thereof may bevaried according to coding rate. Various formats, for example, formats 0and 4 for UL and formats 1, 1A, 1B, 1C, 1D, 2, 2A, 2B, 2C, 3 and 3A forDL, have been defined in 3GPP LTE. Control information such as a hoppingflag, information on RB allocation, modulation coding scheme (MCS),redundancy version (RV), new data indicator (NDI), information ontransmit power control (TPC), cyclic shift demodulation reference signal(DMRS), UL index, channel quality information (CQI) request, DLassignment index, HARQ process number, transmitted precoding matrixindicator (TPMI), precoding matrix indicator (PMI), etc. is selected andcombined based on DCI format and transmitted to a UE as DCI.

In general, the DCI format for a UE depends on the transmission mode(TM) configured for the UE. In other words, only a DCI formatcorresponding to a specific TM may be used for a UE configured in thespecific TM.

A PDCCH is transmitted on an aggregation of one or several consecutivecontrol channel elements (CCEs). The CCE is a logical allocation unitused to provide the PDCCH with a coding rate based on a state of a radiochannel. The CCE corresponds to a plurality of resource element groups(REGs). For example, a CCE corresponds to 9 REGs and an REG correspondsto 4 REs. 3GPP LTE defines a CCE set in which a PDCCH may be located foreach UE. A CCE set from which a UE may detect a PDCCH thereof is calleda PDCCH search space, simply, search space. An individual resourcethrough which the PDCCH may be transmitted within the search space iscalled a PDCCH candidate. A set of PDCCH candidates to be monitored bythe UE is defined as the search space. In 3GPP LTE/LTE-A, search spacesfor DCI formats may have different sizes and include a dedicated searchspace and a common search space. The dedicated search space is aUE-specific search space and is configured for each UE. The commonsearch space is configured for a plurality of UEs. Aggregation levelsdefining the search space is as follows.

TABLE 3 Search space S_(k) ^((L)) Number of Aggregation Size [in PDCCHType level L CCEs] candidates M^((L)) UE- 1  6 6 specific 2 12 6 4  8 26 16 2 Common 4 16 4 8 16 2

A PDCCH candidate corresponds to 1, 2, 4 or 8 CCEs according to CCEaggregation level. An eNB transmits a PDCCH (DCI) on an arbitrary PDCCHcandidate in a search space, and a UE monitors the search space todetect the PDCCH (DCI). Here, monitoring refers to attempting to decodeeach PDCCH in the corresponding search space according to all monitoredDCI formats. The UE may detect the PDCCH thereof by monitoring pluralPDCCHs. Since the UE does not know the position in which the PDCCHthereof is transmitted, the UE attempts to decode all PDCCHs of thecorresponding DCI format for each subframe until a PDCCH having the IDthereof is detected. This process is called blind detection (or blinddecoding (BD)).

The eNB may transmit data for a UE or a UE group through the dataregion. Data transmitted through the data region may be called userdata. For transmission of the user data, a PDSCH may be allocated to thedata region. A PCH and DL-SCH are transmitted through the PDSCH. The UEmay read data transmitted through the PDSCH by decoding controlinformation transmitted through a PDCCH. Information representing a UEor a UE group to which data on the PDSCH is transmitted, how the UE orUE group receives and decodes the PDSCH data, etc. is included in thePDCCH and transmitted. For example, if a specific PDCCH is CRC (cyclicredundancy check)-masked having radio network temporary identify (RNTI)of “A” and information about data transmitted using a radio resource(e.g., frequency position) of “B” and transmission format information(e.g., transport block size, modulation scheme, coding information,etc.) of “C” is transmitted through a specific DL subframe, the UEmonitors PDCCHs using RNTI information and a UE having the RNTI of “A”detects a PDCCH and receives a PDSCH indicated by “B” and “C” usinginformation about the PDCCH.

An RS to be compared with a data signal is necessary for the UE todemodulate a signal received from the eNB. A reference signal refers toa predetermined signal having a specific waveform, which is transmittedfrom the eNB to the UE or from the UE to the eNB and known to both theeNB and UE. The reference signal is also called a pilot. Referencesignals are categorized into a cell-specific RS shared by all UEs in acell and a modulation RS (DM RS) dedicated for a specific UE. A DM RStransmitted by the eNB for demodulation of DL data for a specific UE iscalled a UE-specific RS. Both or one of DM RS and CRS may be transmittedon DL. When only the DM RS is transmitted without CRS, an RS for channelmeasurement needs to be additionally provided because the DM RStransmitted using the same precoder as used for data may be used fordemodulation only. For example, in 3GPP LTE(-A), CSI-RS corresponding toan additional RS for measurement is transmitted to the UE such that theUE may measure channel state information. CSI-RS is transmitted in eachtransmission period corresponding to a plurality of subframes based onthe fact that channel state variation with time is not large, unlike CRStransmitted per subframe.

FIG. 4 illustrates an exemplary UL subframe structure used in 3GPPLTE/LTE-A.

Referring to FIG. 4 , a UL subframe may be divided into a control regionand a data region in the frequency domain. One or more PUCCHs may beallocated to the control region to carry UCI. One or more PUSCHs may beallocated to the data region of the UL subframe to carry user data.

In the UL subframe, subcarriers spaced apart from a DC subcarrier areused as the control region. In other words, subcarriers corresponding toboth ends of a UL transmission bandwidth are assigned to UCItransmission. The DC subcarrier is a component remaining unused forsignal transmission and is mapped to the carrier frequency f0 duringfrequency up-conversion. A PUCCH for a UE is allocated to an RB pairbelonging to resources operating at a carrier frequency and RBsbelonging to the RB pair occupy different subcarriers in two slots.Assignment of the PUCCH in this manner is represented as frequencyhopping of an RB pair allocated to the PUCCH at a slot boundary. Whenfrequency hopping is not applied, the RB pair occupies the samesubcarrier.

The PUCCH may be used to transmit the following control information.

-   -   Scheduling Request (SR): This is information used to request a        UL-SCH resource and is transmitted using On-Off Keying (OOK)        scheme    -   HARQ ACK/NACK: This is a response signal to a DL data packet on        a PDSCH and indicates whether the DL data packet has been        successfully received. A 1-bit ACK/NACK signal is transmitted as        a response to a single DL codeword and a 2-bit ACK/NACK signal        is transmitted as a response to two DL codewords. HARQ-ACK        responses include positive ACK (ACK), negative ACK (NACK),        discontinuous transmission (DTX) and NACK/DTX. Here, the term        HARQ-ACK is used interchangeably with the term HARQ ACK/NACK and        ACK/NACK    -   Channel State Indicator (CSI): This is feedback information        about a DL channel. Feedback information regarding MIMO includes        a rank indicator (RI) and a precoding matrix indicator (PMI).

The quantity of control information (UCI) that a UE may transmit througha subframe depends on the number of single carrier frequency divisionmultiple access (SC-FDMA) symbols available for control informationtransmission. The SC-FDMA symbols available for control informationtransmission correspond to SC-FDMA symbols other than SC-FDMA symbols ofthe subframe, which are used for reference signal transmission. In thecase of a subframe in which a sounding reference signal (SRS) isconfigured, the last SC-FDMA symbol of the subframe is excluded from theSC-FDMA symbols available for control information transmission. Areference signal is used to detect coherence of the PUCCH. The PUCCHsupports various formats according to information transmitted thereon.

Table 4 shows the mapping relationship between PUCCH formats and UCI inLTE/LTE-A.

TABLE 4 Number of bits per PUCCH Modulation subframe, format schemeM_(bit) Usage Etc. 1 N/A N/A SR (Scheduling Request) 1a BPSK  1 ACK/NACKor One SR + ACK/NACK codeword 1b QPSK  2 ACK/NACK or Two SR + ACK/NACKcodeword 2 QPSK 20 CQI/PMI/RI Joint coding ACK/NACK (extended CP) 2aQPSK + 21 CQI/PMI/RI + Normal CP BPSK ACK/NACK only 2b QPSK + 22CQI/PMI/RI + Normal CP QPSK ACK/NACK only 3 QPSK 48 ACK/NACK or SR +ACK/NACK or CQI/PMI/RI + ACK/NACK

Referring to Table 4, PUCCH formats 1/1a/1b are used to transmitACK/NACK information, PUCCH format 2/2a/2b are used to carry CSI such asCQI/PMI/RI and PUCCH format 3 is used to transmit ACK/NACK information.

PUCCH format 3 uses block spreading. Block spreading is a technique ofmultiplexing modulation symbol sequences obtained by modulating amulti-bit ACK/NACK by using block spreading codes. For block spreading,SC-FDMA may be used. SC-FDMA refers to a transmission scheme in whichdiscrete Fourier transform (DFT) spreading (or fast Fourier transform(FFT)) is accompanied by inverse fast Fourier transform (IFFT).

In PUCCH format 3, a symbol sequence (e.g., an ACK/NACK symbol sequence)is spread in the time domain by a block spreading code, fortransmission. A block spreading code may be an orthogonal cover code(OCC). Control signals from multiple UEs may be multiplexed by blockspreading codes. Compared to PUCCH format 2 in which one symbol sequenceis transmitted across a time area and UEs are multiplexed by usingcyclic shifts (CSs) of a constant amplitude zero auto-correlation(CAZAC) sequence, a symbol sequence including one or more symbols istransmitted across a frequency area in each data symbol and UEs aremultiplexed by spreading symbol sequences with block spreading codes inthe time domain in PUCCH format 3.

Reference Signal (RS)

When a packet is transmitted in a wireless communication system, signaldistortion may occur during transmission since the packet is transmittedthrough a radio channel. To correctly receive a distorted signal at areceiver, the distorted signal needs to be corrected using channelinformation. To detect channel information, a signal known to both atransmitter and the receiver is transmitted and channel information isdetected with a degree of distortion of the signal when the signal isreceived through a channel. This signal is called a pilot signal or areference signal.

When data is transmitted/received using multiple antennas, the receivermay receive a correct signal only when the receiver is aware of achannel state between each transmit antenna and each receive antenna.Accordingly, a reference signal needs to be provided per transmitantenna, more specifically, per antenna port.

Reference signals may be classified into an UL reference signal and a DLreference signal. In LTE, the UL reference signal includes:

i) a demodulation reference signal (DMRS) for channel estimation forcoherent demodulation of information transmitted through a PUSCH and aPUCCH; and

ii) a sounding reference signal (SRS) used for an eNB to measure ULchannel quality at a frequency of a different network.

The DL reference signal includes:

i) a cell-specific reference signal (CRS) shared by all UEs in a cell;

ii) a UE-specific reference signal for a specific UE only;

iii) a DMRS transmitted for coherent demodulation when a PDSCH istransmitted;

iv) a channel state information reference signal (CSI-RS) for deliveringchannel state information (CSI) when a DL DMRS is transmitted;

v) a multimedia broadcast single frequency network (MBSFN) referencesignal transmitted for coherent demodulation of a signal transmitted inMBSFN mode; and

vi) a positioning reference signal used to estimate geographic positioninformation of a UE.

Reference signals may be classified into a reference signal for channelinformation acquisition and a reference signal for data demodulation.The former needs to be transmitted in a wide band as it is used for a UEto acquire channel information on DL transmission and received by a UEeven if the UE does not receive DL data in a specific subframe. Thisreference signal is used even in a handover situation. The latter istransmitted along with a corresponding resource by an eNB when the eNBtransmits a DL signal and is used for a UE to demodulate data throughchannel measurement. This reference signal needs to be transmitted in aregion in which data is transmitted.

CSI Reporting

In the 3GPP LTE(-A) system, a user equipment (UE) is defined to reportCSI to a BS. Herein, the CSI collectively refers to informationindicating the quality of a radio channel (also called a link) createdbetween a UE and an antenna port. The CSI includes, for example, a rankindicator (RI), a precoding matrix indicator (PMI), and a channelquality indicator (CQI). Herein, the RI, which indicates rankinformation about a channel, refers to the number of streams that a UEreceives through the same time-frequency resource. The RI value isdetermined depending on long-term fading of the channel, and is thususually fed back to the BS by the UE with a longer period than for thePMI and CQI. The PMI, which has a value reflecting the channel spaceproperty, indicates a precoding index preferred by the UE based on ametric such as SINR. The CQI, which has a value indicating the intensityof a channel, typically refers to a receive SINR which may be obtainedby the BS when the PMI is used.

The UE calculates, based on measurement of the radio channel, apreferred PMI and RI from which an optimum or highest transmission ratemay be derived when used by the BS in the current channel state, andfeeds back the calculated PMI and RI to the BS. Herein, the CQI refersto a modulation and coding scheme providing an acceptable packet errorprobability for the PMI/RI that is fed back.

Meanwhile, in the LTE-A system expected to include finer MU-MIMO andexplicit CoMP operations, current CSI feedback is defined in LTE andcannot sufficiently support such operations to be newly employed. As therequirements for CSI feedback accuracy become complicated to obtainsufficient MU-MIMO or CoMP throughput gain, they agreed to configure PMIwith two types of long term/wideband PMI (W₁) and short term/subband PMI(W₂). So to speak, final PMI is expressed as a function of W₁ and W₂.For example, final PMI W may be defined as follows: W=W₁*W₂ or W=W₂*W₁.Hence, in LTE-A, CSI shall be configured with RI, W₁, W₂ and CQI.

In the 3GPP LTE(-A) system, an UL channel used for CSI transmission isconfigured as shown in Table 5.

TABLE 5 Periodic CSI Aperiodic CSI Scheduling scheme transmissiontransmission Frequency non-selective PUCCH — Frequency selective PUCCHPUSCH

Referring to Table 5, CSI may be transmitted with a periodicity definedin a higher layer, using a physical UL control channel (PUCCH). Whenneeded by the scheduler, a physical UL shared channel (PUSCH) may beaperiodically used to transmit the CSI. Transmission of the CSI over thePUSCH is possible only in the case of frequency selective scheduling andaperiodic CSI transmission. Hereinafter, CSI transmission schemesaccording to scheduling schemes and periodicity will be described.

1) Transmitting the CQI/PMI/RI over the PUSCH after receiving a CSItransmission request control signal (a CSI request)

A PUSCH scheduling control signal (UL grant) transmitted over a PDCCHmay include a control signal for requesting transmission of CSI. Thetable below shows modes of the UE in which the CQI, PMI and RI aretransmitted over the PUSCH.

TABLE 6 PMI Feedback Type No PMI Single PMI Multiple PMI PUSCH WidebandMode 1-2 CQI (wideband RI Feedback CQI) 1st wideband CQI(4bit) Type 2ndwideband CQI(4bit) if RI > 1 N*Subband PMI(4bit) (N is the total # ofsubbands) (if 8Tx Ant. N*subband W2 + wideband W1) UE Mode 2.0 Mode 2-2Selected RI (only for Open- RI (subband loop SM) 1st widebandCQI(4bit) + CQI) 1st wideband Best-M CQI(2bit) CQI(4bit) + Best-M 2ndwideband CQI(4bit) + CQI(2bit) Best-M CQI(2bit) if RI > 1 (Best-M CQI:An Best-M index (L bit) average CQI for M Wideband PMI(4bit) + SBsselected from Best-M PMI(4bit) among N SBs) (if 8Tx Ant. wideband W2 +Best-M index (L bit) Best-M W2 + wideband W1) Higher Mode 3.0 Mode 3-1Mode 3-2 Layer- RI fonlv for Open- RI RI configured loop SM) 1stwideband CQI(4bit) + 1st wideband CQI(4bit) + (subband 1st widebandN*subbandCQI(2bit) N*subbandCQI(2bit) CQI) CQI(4bit) + 2nd widebandCQI(4bit) + 2nd wideband CQI(4bit) + N*subbandCQI(2bit)N*subbandCQI(2bit) if RI > 1 N*subbandCQI(2bit) if RI > 1 WidebandPMI(4bit) N*Subband PMI(4bit) (if 8Tx Ant. wideband W2 + (N is the total# of wideband W1) subbands) (if 8Tx Ant. N*subband W2 + wideband W1)

The transmission modes in Table 6 are selected in a higher layer, andthe CQI/PMI/RI are all transmitted in a PUSCH subframe. Hereinafter, ULtransmission methods for the UE according to the respective modes willbe described.

Mode 1-2 represents a case where precoding matrices are selected on theassumption that data is transmitted only in subbands. The UE generates aCQI on the assumption of a precoding matrix selected for a system bandor a whole band (set S) designated in a higher layer. In Mode 1-2, theUE may transmit a CQI and a PMI value for each subband. Herein, the sizeof each subband may depend on the size of the system band.

A UE in Mode 2-0 may select M preferred subbands for a system band or aband (set S) designated in a higher layer. The UE may generate one CQIvalue on the assumption that data is transmitted for the M selectedsubbands. Preferably, the UE additionally reports one CQI (wideband CQI)value for the system band or set S. If there are multiple codewords forthe M selected subbands, the UE defines a CQI value for each codeword ina differential form.

In this case, the differential CQI value is determined as a differencebetween an index corresponding to the CQI value for the M selectedsubbands and a wideband (WB) CQI index.

The UE in Mode 2-0 may transmit, to a BS, information about thepositions of the M selected subbands, one CQI value for the M selectedsubbands and a CQI value generated for the whole band or designated band(set S). Herein, the size of a subband and the value of M may depend onthe size of the system band.

A UE in Mode 2-2 may select positions of M preferred subbands and asingle precoding matrix for the M preferred subbands simultaneously onthe assumption that data is transmitted through the M preferredsubbands. Herein, a CQI value for the M preferred subbands is definedfor each codeword. In addition, the UE additionally generates a widebandCQI value for the system band or a designated band (set S).

The UE in Mode 2-2 may transmit, to the BS, information about thepositions of the M preferred subbands, one CQI value for the M selectedsubbands and a single PMI for the M preferred subbands, a wideband PMI,and a wideband CQI value. Herein, the size of a subband and the value ofM may depend on the size of the system band.

A UE in Mode 3-0 generates a wideband CQI value. The UE generates a CQIvalue for each subband on the assumption that data is transmittedthrough each subband. In this case, even if RI>1, the CQI valuerepresents only the CQI value for the first codeword.

A UE in Mode 3-1 generates a single precoding matrix for the system bandor a designated band (set S). The UE generates a CQI subband for eachcodeword on the assumption of the single precoding matrix generated foreach subband. In addition, the UE may generate a wideband CQI on theassumption of the single precoding matrix. The CQI value for eachsubband may be expressed in a differential form. The subband CQI valueis calculated as a difference between the subband CQI index and thewideband CQI index. Herein, the size of each subband may depend on thesize of the system band.

A UE in Mode 3-2 generates a precoding matrix for each subband in placeof a single precoding matrix for the whole band, in contrast with the UEin Mode 3-1.

2) Periodic CQI/PMI/RI transmission over PUCCH

The UE may periodically transmit CSI (e.g., CQI/PMI/PTI (precoding typeindicator) and/or RI information) to the BS over a PUCCH. If the UEreceives a control signal instructing transmission of user data, the UEmay transmit a CQI over the PUCCH. Even if the control signal istransmitted over a PUSCH, the CQI/PMI/PTI/RI may be transmitted in oneof the modes defined in the following table.

TABLE 7 PMI feedback type No PMI Single PMI PUCCH CQI Wideband Mode 1-0Mode 1-1 feedback type (wideband CQI) UE selective Mode 2-0 Mode 2 -1(subband CQI)

A UE may be set in transmission modes as shown in Table 7. Referring toTable 7, in Mode 2-0 and Mode 2-1, a bandwidth part (BP) may be a set ofsubbands consecutively positioned in the frequency domain, and cover thesystem band or a designated band (set S). In Table 7, the size of eachsubband, the size of a BP and the number of BPs may depend on the sizeof the system band. In addition, the UE transmits CQIs for respectiveBPs in ascending order in the frequency domain so as to cover the systemband or designated band (set S).

The UE may have the following PUCCH transmission types according to atransmission combination of CQI/PMI/PTI/RI.

i) Type 1: the UE transmits a subband (SB) CQI of Mode 2-0 and Mode 2-1.

ii) Type 1a: the UE transmits an SB CQI and a second PMI.

iii) Types 2, 2b and 2c: the UE transmits a WB-CQI/PMI.

iv) Type 2a: the UE transmits a WB PMI.

v) Type 3: the UE transmits an RI.

vi) Type 4: the UE transmits a WB CQI.

vii) Type 5: the UE transmits an RI and a WB PMI.

viii) Type 6: the UE transmits an RI and a PTI.

ix) Type 7: the UE transmits a CRI (CSI-RS resource indicator) and anRI.

x) Type 8: the UE transmits a CRI, an RI and a WB PMI.

xi) Type 9: the UE transmits a CRI, an RI and a PTI (precoding typeindication).

xii) Type 10: the UE transmits a CRI.

When the UE transmits an RI and a WB CQI/PMI, the CQI/PMI aretransmitted in subframes having different periodicities and offsets. Ifthe RI needs to be transmitted in the same subframe as the WB CQI/PMI,the CQI/PMI are not transmitted.

Aperiodic CSI Request

If a carrier aggregation (CA) environment is considered, a 2-bit CSIrequest field is used in DCI format 0 or 4, for an aperiodic CSIfeedback in the current LTE standards. If a plurality of serving cellsare configured for a UE in the CA environment, the UE interprets the CSIrequest field in 2 bits. If one of TM 1 to TM 9 is configured for everycomponent carrier (CC), an aperiodic CSI feedback is triggered accordingto values listed in Table 8 below. If TM 10 is configured for at leastone of all CCs, an aperiodic CSI feedback is triggered according tovalues listed in Table 9 below.

TABLE 8 Values of CSI request field Description ‘00’ Aperiodic CSIreporting is not triggered ‘01’ Aperiodic CSI reporting is triggered forserving cell ‘10’ Aperiodic CSI reporting is triggered for a first setof serving cells configured by higher layer ‘11’ Aperiodic CSI reportingis triggered for a 1 second set of serving cells configured by higherlayer

TABLE 9 Values of CSI request field Description ‘00’ Aperiodic CSIreporting is not triggered ‘01’ Aperiodic CSI reporting is triggered forCSI process set configured for serving cell by higher layer ‘10’Aperiodic CSI reporting is triggered for a first set of CSI processesconfigured by higher layer ‘11’ Aperiodic CSI reporting is triggered fora second set of CSI processes configured by higher layer

(Carrier Aggregation (CA)

CA is a technique of using one logical wide frequency band byaggregating a plurality of frequency blocks or (logical) cells, eachincluding a UL resource (or UL component carrier (CC)) and/or a DLresource (or DL CC) by a UE, so that a wireless communication system mayuse a wider frequency band.

One DL CC and one UL CC are used in the LTE system, whereas a pluralityof CCs are available in the LTE-A system. For data channel scheduling bya control channel, legacy linked carrier/self-carrier scheduling andcross-carrier scheduling (CCS) are available.

More specifically, in linked carrier/self-carrier scheduling, a controlchannel transmitted in a specific CC schedules only a data channel inthe specific CC as in the legacy LTE system using a single CC.

In CCS, a control channel transmitted in a primary CC schedules a datachannel transmitted in the primary CC or any other CC by means of acarrier indicator field (CIF).

Next-Generation LTE-A System

As more and more communication devices require a larger communicationcapacity, there is a need for enhanced mobile broadband communication(eMBB) beyond the legacy radio access technology (RAT) in anext-generation communication system under discussion. In addition,massive machine type communications (MTC) that provide a variety ofservices anywhere and anytime by interconnecting multiple devices andobjects is one of important issues to be considered for next-generationcommunications. In consideration of services/UEs sensitive toreliability and latency, ultra-reliable and low latency communication(URLLC) is being discussed for the next-generation communication system.

In the next-generation system, various (lengths of) transmission timeintervals (TTIs) may be configured for all or specific physical channelsto satisfy the requirements of various application fields. Inparticular, a TTI in which a physical channel such as aPDCCH/PDSCH/PUSCH/PUCCH is transmitted may be set less than 1 msec toreduce communication latency between an eNB and a UE depending onscenarios (the PDCCH/PDSCH/PUSCH/PUCCH is referred to as asPDCCH/sPDSCH/sPUSCH/sPUCCH).

For a single or multiple UEs, a plurality of physical channels may bepresent in one subframe (e.g., 1 msec), and each channel may have adifferent TTI (length). The following embodiments will be describedbased on the LTE system for convenience of description. In this case, aTTI may be set to 1 msec, which is the length of a normal subframe ofthe LTE system (such a TTI is referred to as a normal TTI). A short TTImeans a TTI shorter than the normal TTI and includes one or multipleOFDM or SC-FDMA symbols. Although the present disclosure assumes theshort TTI (i.e., a TTI shorter than one subframe) for convenience ofdescription, the present disclosure may be extended and applied when theTTI is longer than one subframe or has a length equal to or longer than1 ms. The present disclosure may also be extended and applied when thenext-generation system introduces the short TTI by increasing thesubcarrier spacing. Although the present disclosure is described basedon the LTE system for convenience of description, the disclosure is alsoapplicable to a technology that uses a different waveform/framestructure such as new radio access technology (RAT). In general, thepresent disclosure assumes the use of a sTTI (<1 msec), a long TTI (=1msec), and a longer TTI (>1 msec). Although the following embodimentsare described based on multiple UL channels having different TTIlengths, numerologies, and/or processing times, it is apparent that theembodiments are applicable to multiple UL/DL channels with differentservice requirements, latency, and/or scheduling units.

To satisfy a reduction in the above-described latency, i.e., lowlatency, a TTI, which is a minimum unit for data transmission, needs tobe newly designed to be reduced to a shortened TTI (sTTI) which is equalto or less than 0.5 msec (ms). For example, as illustrated in FIG. 5 ,in order to reduce user-plane (U-plane) latency to 1 ms until the UEcompletes transmission of ACK/NACK (A/N) since the eNB has startedtransmission of data (a PDCCH and a PDSCH), the sTTI may be configuredin units of about 3 OFDM symbols.

In a DL environment, a PDCCH for data transmission/scheduling within thesTTI (i.e., a sPDCCH) and a PDSCH for transmitting data within the sTTI(i.e., a sPDSCH) may be transmitted. For example, as illustrated in FIG.6 , a plurality of sTTIs may be configured using different OFDM symbolsin one subframe. Characteristically, OFDM symbols in which legacychannels are transmitted may be excluded from OFDM symbols constitutinga sTTI. The sPDCCH and the sPDSCH within the sTTI may be transmitted indifferent OFDM symbol regions by being time-division-multiplexed (TDMed)or may be transmitted in different PRBs or on different frequencyresources by being frequency-division-multiplexed (FDMed).

In a UL environment, data may be transmitted/scheduled in the sTTI as inthe DL case. In this case, channels corresponding to the PUCCH and thePUSCH, which are based on the normal TTI, may be referred to as sPUCCH′and sPUSCH′, respectively.

In the present disclosure, a description is given based on an LTE/LTE-Asystem. In a legacy LTE/LTE-A system, a 1-ms subframe may include 14OFDM symbols in the case of a normal CP. If the 1-ms subframe isconfigured by TTIs shorter than 1 ms, one subframe may include aplurality of TTIs. As in examples illustrated in FIGS. 7A to 7D, 2symbols, 3 symbols, 4 symbols, or 7 symbols may constitute one TTI.Although not illustrated, the case in which one symbol constitutes oneTTI may be considered. If one symbol constitutes one TTI unit, 12 TTIsare generated under the assumption that legacy PDCCHs are transmitted intwo OFDM symbols. Similarly, as illustrated in FIG. 7A, if two symbolsconstitute one TTI unit, 6 TTIs may be generated. As illustrated in FIG.7B, if 3 symbols constitute one TTI unit, 4 TTIs may be generated. Asillustrated in FIG. 7C, if 4 symbols constitute one TTI unit, 3 TTIs maybe generated. In this case, it is assumed that legacy PDCCHs aretransmitted in the first starting two OFDM symbols.

As illustrated in FIG. 7D, in the case in which 7 symbols constitute oneTTI, 7 symbols including legacy PDCCHs may constitute one TTI and 7subsequent symbols may constitute one TTI. If one TTI includes 7symbols, a UE supporting a sTTI assumes that, in a TTI located at afront part of one subframe (i.e., the first slot), front two OFDMsymbols in which legacy PDCCHs are transmitted are punctured orrate-matched and that data of the UE and/or control information istransmitted in 5 symbols subsequent to the front two symbols. Incontrast, the UE assumes that, in a TTI located at a rear part of onesubframe (i.e., the second slot), data and/control information may betransmitted in all of 7 symbols without a punctured or rate-matchedresource region.

The present disclosure considers a sTTI structure in which a sTTIconsisting of two OFDM symbols (OSs) and a sTTI consisting of three OSscoexist in one subframe as illustrated in FIGS. 8A and 8B. The sTTIconsisting of two or three OSs may be simply defined as a two-symbolsTTI (or a two-OS sTTI). In addition, a two-symbol sTTI and athree-symbol sTTI may be referred to as a two-symbol TTI and athree-symbol TTI, respectively. It should be noted that each of thesTTIs is shorter than the legacy TTI, i.e., 1 ms TTI. That is, the term“TTI” used herein may indicate the sTTI as well. The object of thepresent disclosure is to provide a communication method in a systemusing a TTI shorter than the legacy TTI, irrespective of their names.

Herein, the numerology may refer to a TTI length or subcarrier spacingto be applied to a wireless communication system, a parameter indicatinga fixed TTI length or fixed subcarrier spacing, a communicationarchitecture or system based thereon.

In sTTI pattern <3,2,2,2,2,3> illustrated in FIG. 8A, the sPDCCH may betransmitted depending on the number of PDCCH symbols. In sTTI pattern<2,3,2,2,2,3> illustrated in FIG. 8B, it may be difficult to transmitthe sPDCCH due to the legacy PDCCH region.

New Radio Technology (NR)

The structure, operations, or functions of the 3GPP LTE(-A) system havebeen described above. For NR, the structure, operations, or functions ofthe 3GPP LTE(-A) system may be modified to a certain extent or realizedor configured in a different manner, which will be described in brief.

In the NR system, a DL transmission and a UL transmission are performedin 10-ms frames each including 10 subframes. Accordingly, one subframeis 1 ms long. Each frame is divided into two half-frames.

One subframe includes as many consecutive OFDM symbols asNsymbsubframe,μ(=Nsymbslot×Nslotsubframe,μ) where Nsymbslot representsthe number of symbols per slot, μ represents an OFDM numerology, andNslotsubframe,μ represents the number of slots per subframe with respectto μ. In NR, multiple OFDM numerologies may be supported as listed inTable 10.

TABLE 10 μ Δf = 2^(μ) · 15 [kHz] Cyclic prefix 0 15 Normal 1 30 Normal 260 Normal, Extended 3 120  Normal 4 240  Normal

In Table 10, Δf represents a subcarrier spacing (SCS). μ and a cyclicprefix (CP) for a DL carrier bandwidth part (BWP) and μ and a CP for aUL carrier BWP may be configured for a UE by UL signaling.

Table 11 lists the number of symbols per slot, Nsymbslot, the number ofslots per frame, Nslotframe,μ and the number of slots per subframe,Nslotsubframe,μ for each SCS in a normal CP case.

TABLE 11 μ N_(symb) ^(slot) N_(slot) ^(frame,μ) N_(slot) ^(subframe,μ) 014 10  1 1 14 20  2 2 14 40  4 3 14 80  8 4 14 160  16 5 14 320  32

Table 12 lists the number of symbols per slot, Nsymbslot, the number ofslots per frame, Nslotframe,μ and the number of slots per subframe,Nslotsubframe,μ for each SCS in an extended CP case.

TABLE 12 μ N_(symb) ^(slot) N_(slot) ^(frame,μ) N_(slot) ^(subframe,μ) 212 40 4

As such, the number of slots per subframe may vary according to an SCSin the NR system. Each of the OFDM symbols of each slot may correspondto one of DL (D), UL (U), and flexible (X). A DL transmission may takeplace in a D or X symbol, and a UL transmission may take place in a U orX symbol. Flexible resources (e.g., an X symbol) may also be referred toas reserved resources, other resources, or unknown resources.

In NR, one RB is defined by 12 subcarriers in the frequency domain. OneRB may include multiple OFDM symbols. An RE is defined by one subcarrierby one OFDM symbol. Therefore, there are 12 REs in one OFDM symbol ofone RB.

A carrier BWP may be defined as a set of contiguous PRBs. The termcarrier BWP may also be referred to shortly as BWP. Up to four BWPs maybe configured for a UE on each of UL and DL. Although multiple BWPs areconfigured, one BWP is activated during a given time period. However,when a supplementary UL (SUL) is configured for the UE, four more BWPsmay be configured on the SUL, and one of the BWPs may be activatedduring a given time period. The UE does not expect to receive a PDSCH, aPDCCH, a CSI-RS, or a tracking reference signal (TRS) outside theactivated DL BWP. Further, the UE does not expect to receive a PUSCH ora PUCCH outside the activated UL BWP.

FIG. 9 is a diagram illustrating a self-contained subframe structureapplicable to the present disclosure.

In FIG. 9 , the hatched area (e.g., symbol index=0) represents a DLcontrol region, and the black area (e.g., symbol index=13) represents aUL control region. The other area (e.g., symbol index=1 to 12) may beused for DL or UL data transmission.

Based on the self-contained slot structure, a BS and a UE maysequentially perform DL transmission and UL transmission in one slot.That is, the BS and the UE may transmit and receive not only DL data butalso UL ACK/NACK for the DL data in one slot. The self-contained slotstructure may reduce a time required for data retransmission when a datatransmission error occurs, thereby minimizing the latency of the finaldata transmission.

In the self-contained slot structure, a time gap with a predeterminedlength is required to allow the BS and the UE to switch fromtransmission mode to reception mode or vice versa. To this end, someOFDM symbols at the time of switching from DL to UL may set as a guardperiod (GP).

Although it is described that the self-contained slot structure includesboth the DL and UL control regions, these control regions may beselectively included in the self-contained slot structure. In otherwords, the self-contained slot structure according to the presentdisclosure may include either the DL control region or the UL controlregion as well as both the DL and UL control regions as shown in FIGS.7A to 7D.

For example, a slot may have various slot formats. In this case, OFDMsymbols in each slot can be classified into a DL symbol (denoted by‘D’), a flexible symbol (denoted by ‘X’), and a UL symbol (denoted by‘U’).

Thus, a UE may assume that DL transmission occurs only in symbolsdenoted by ‘D’ and ‘X’ in a DL slot. Similarly, the UE may assume thatUL transmission occurs only in symbols denoted by ‘U’ and ‘X’ in a ULslot.

The next-generation system aims to use wide frequency bands and supportvarious services or requirements. For example, URLLC, which is one ofthe representative scenarios regarding 3GPP NR requirements, requireslow latency and high reliability. Specifically, the URLLC requires thatthat user plane latency of 0.5 ms is supported and X-byte data istransmitted within 1 ms with an error rate less than 10{circumflex over( )}−5. Generally, the traffic volume of eMBB is high, but the file sizeof URLLC traffic is less than tens or hundreds of bytes and sporadicallyoccurs. Thus, for the eMBB, a transmission method capable of maximizingthe transfer rate and minimizing the overhead of control information isrequired, but for the URLLC, a transmission method capable of using ashort scheduling time unit and guaranteeing reliability is required.

Depending on application fields or traffic types, various reference timeunits may be assumed/used to transmit and receive a physical channel.The reference time unit may be a basic unit for scheduling a specificphysical channel and vary depending on the number of symbols included ina corresponding scheduling unit and/or subcarrier spacing. Inembodiments of the present disclosure, a slot or a mini-slot is used asthe reference time unit for convenience of description. The slot mayrefer to a basic scheduling unit used for normal data traffic (e.g.,eMBB). The time duration of the mini-slot may be shorter than that ofthe slot in the time domain. The mini-slot may refer to a basicscheduling unit used for special traffic or communication (e.g., URLLC,unlicensed band, millimeter wave, etc.). However, this is merelyexemplary, and it is apparent that the present disclosure may beextended and applied when a physical channel is transmitted and receivedbased on the mini-slot in the eMBB or when a physical channel istransmitted and received based on the slot in the URLLC or othercommunication methods.

Fast CSI Reporting

To support more strict reliability and latency requirements, CSIfeedback needs to become faster and more accurate. That is, fast andaccurate CSI feedback may allow a network to efficiently schedule a UE.To this end, it may be regulated that the UE transmits a CSI report on aspecific cell and/or CSI process earlier than a conventional CSI report,which is based on a CSI request in a UL grant. In particular, adifferent service type and/or block error rate (BLER) requirement may beconfigured for each cell and/or CSI process. In addition, it may beregulated that CSI feedback for a specific service type and/or BLERrequirement is provided at a timing different from a UL-SCH transmissiontiming scheduled by the UL grant (for example, at a timing earlier thanthat of the conventional CSI report based on the CSI request in the ULgrant). In the present specification, “fast CSI reporting” means thatCSI is reported at a timing earlier than that defined in the relatedart.

It may be regulated that PUSCH transmission for fast CSI reporting isperformed at a timing different from the UL-SCH transmission timingscheduled by the UL grant. In particular, when multiple PUSCHs aretransmitted based on the corresponding UL grant, one may be ‘A-CSI onlyPUSCH’ transmission and another may be PUSCH with UL-SCH′ transmission.The A-CSI only PUSCH transmission refers to PUSCH transmission includingonly A-CSI, and the PUSCH with UL-SCH transmission refers to PUSCHtransmission including a UL-SCH depending on a UL grant (i.e., normalPUSCH transmission). For example, assuming that the timing of theUL-grant-to-PUSCH with UL-SCH transmission is x subframes (or slots) andthe timing of the A-CSI only PUSCH transmission from the UL grant is ysubframes (or slots), y may be less than x (y<x). Alternatively, it maybe regulated that the fast CSI reporting is enabled only when thecondition for the A-CSI only PUSCH transmission is satisfied.

The fast CSI reporting may be performed on the PUSCH or a channel suchas the PUCCH. Which channel is used for the fast CSI reporting may beconfigured by a higher layer signal or indicated by DCI. When the PUSCHis used for the fast CSI reporting, RB allocation may follow resourceallocation indicated by UL grant DCI. However, in this case, if manyresources are allocated for UL-SCH scheduling, the same amount ofresources are used for the fast CSI reporting, and it may causeexcessive resource waste. Accordingly, some resources in the resourceallocation indicated by the UL grant DCI may be used for the fast CSIreporting. For example, it may be regulated that the fast CSI reportingis performed using a specific number of RBs, which arepredefined/preconfigured, configured by the higher layer signal, orindicated by the DCI, from an RB with the lowest (or highest) RB indexamong allocated resources. As another example, it may be regulated thatthe fast CSI reporting is performed using resources corresponding to astarting RB index and length, which are predefined/preconfigured,configured by the higher layer signal, or indicated by the DCI. Asanother method, separate resources for the fast CSI reporting may beconfigured by the higher layer signal or indicated by the DCI. As afurther method, if a PUSCH scheduled by the previous UL grant is presentat the timing of the fast CSI reporting, it may be piggybacked on thecorresponding PUSCH. In this case, if the corresponding PUSCH includesCSI triggered by the previous UL grant, it may be regulated that onlythe CSI corresponding to the fast CSI reporting is transmitted byoverriding the CSI triggered by the previous UL grant.

When the PUSCH is used for the fast CSI reporting, an MCS indicated bythe UL grant DCI may be used. However, to increase the reliability ofCSI transmission, it may be regulated that a predetermined modulationorder (e.g., QPSK) is used for the fast CSI reporting.

When the fast CSI reporting is triggered by the CSI request, it may beregulated that the PUCCH is used for the fast CSI reporting. To thisend, a PUCCH resource for the fast CSI reporting may be configured bythe higher layer signal or indicated by the CSI request. In particular,a specific PUCCH resource may be linked to a specific field in the CSIrequest. If there is another PUCCH for different UCI at the timing ofthe fast CSI reporting, aggregation may be performed on the PUCCH, andin this case, format adaptation may be defined. For example, if thetiming of HARQ-ACK based on PUCCH format 1 collides with thetransmission timing of the fast CSI reporting, it may be regulated thatPUCCH format 3, 4, or 5 or a new PUCCH format (capable of supporting alarge payload) is used for the format adaptation.

It may be regulated that the fast CSI reporting is performed only in thecase of a CSI report on a cell or CSI process with a specific targetBLER, a specific service type (e.g., URLLC), a specific TTI length,and/or a specific numerology. In particular, when the CSI request istransmitted, the target BLER, service type, TTI length, and/ornumerology may be linked to each state in the CSI request, and the CSIreporting timing may be determined for each state. As another method,the reporting timing for each state may be explicitly indicated by thehigher layer signal or implicitly mapped so that the CSI reportingtiming may be determined for each state. As a further method, it may beregulated that the target BLER, service type, TTI length, and/ornumerology is linked to each cell and/or CSI process, and each celland/or CSI process has a different reporting timing. For example,assuming that the timing of the UL-grant-to-PUSCH with UL-SCHtransmission is four subframes (or slots) and the timing of the A-CSIonly PUSCH transmission is two subframes (or slots), if CSI processes a,b, and c, which correspond to specific states of CSI request bits, haveBLER requirements of 10{circumflex over ( )}−1, 10{circumflex over( )}−1, and 10{circumflex over ( )}−5, respectively, the UE may reportCSI process c after two subframes (or slots) from when receiving the ULgrant DCI including the CSI request and report CSI processes a and bafter four subframes (or slots).

The timing of a reference resource for performing measurement for thefast CSI reporting or the CSI reporting for the cell or CSI process withthe specific target BLER, the specific service type (e.g., URLLC), thespecific TTI length, and/or the specific numerology may be defined to bedifferent from that of a conventional reference resource (the former maybe shorter than the latter). In general, a CSI reference resource forthe cell or CSI process with the specific target BLER, the specificservice type (e.g., URLLC), the specific TTI length, and/or the specificnumerology may have a different timing from the conventional one (it mayhave a shorter timing than the conventional one). The timing of the CSIreference resource may be linked to each state in the CSI request,configured by the higher layer signal, or indicated by the DCI.Alternatively, the timing of the CSI reference resource may be linked toeach cell and/or CSI process, configured by the higher layer signal, orindicated by the DCI.

A TTI length (i.e., scheduling unit size) and/or a numerology used as areference for PDSCH CQI calculation on the reference resource on whichthe measurement for the fast CSI reporting or the CSI reporting for thecell or CSI process with the specific target BLER, the specific servicetype (e.g., URLLC), the specific TTI length, and/or the specificnumerology is performed may be configured independently of those fornormal CSI reporting. In addition, an RS (e.g., a CSI-RS different fromthat for the normal CSI reporting, a CSI-RS resource index, aCSI-RS+DMRS, and/or a DMRS only) used as the reference for the PDSCH CQIcalculation on the reference resource on which the measurement for thefast CSI reporting is performed may be configured independently of thoseof the normal CSI reporting.

When the target BLER, service type (e.g., URLLC), TTI length, and/ornumerology of CSI feedback on a specific cell or CSI process varies, thecontent of the corresponding CSI feedback may also vary. In particular,it may be regulated that some of the content of a CSI reporting modeconfigured for the corresponding cell/CSI process is reported. Forexample, the UE may report only an RI or a specific subband CQI/PMI. Asanother method, it may be regulated that only the content of a(predefined or signaled) compact mode (e.g., a wideband report, mode 1-0or 1-1, etc.) is reported instead of following the CSI reporting modeconfigured for the corresponding cell/CSI process. The CSI reportingmode of the corresponding cell/CSI process or the content (set) to beactually transmitted in the corresponding cell/CSI process may be linkedto a CSI request field in the DCI or a field equivalent thereto, and theUE may determine the content of the CSI reporting based thereon. As afurther method, the target BLER, service type (e.g., URLLC), TTI length,and/or numerology may be interpreted differently for the same CSIreporting mode. More specifically, the content set of the CSI reportingmode, the subband size, the number of pieces of actually reportedsubband CSI, and/or the bit field size of each content may vary.

CSI Update/Calculation Capability

To support an operation of triggering/reporting a suitable amount of CSIfeedback, the UE may need to report its maximum simultaneous CSIupdate/calculation capability to the network. In particular, it may beregulated that the UE reports to the network the maximum simultaneousCSI update/calculation capability for each target BLER, service type,TTI length, numerology, and/or processing time or for each combinationthereof, using the number of cells or CSI processes. Alternatively, itmay be regulated that the UE reports to the network the capability forthe maximum number of simultaneously reported CSI reports for eachtarget BLER, service type, TTI length, numerology, and/or processingtime or for each combination thereof. The above capability signaling maybe defined differently and independently per band or per bandcombination. The UE is not required to update cells or CSI processesover the maximum simultaneous CSI update/calculation capability. Inother words, the UE may update cells and CSI processes within themaximum simultaneous CSI update/calculation capability.

It may be regulated that a CSI report on a cell or CSI process with aspecific target BLER, a specific service type (e.g., URLLC), a specificTTI length, a specific numerology, and/or a specific processing time isprioritized and updated first. In particular, it may be regulated a CSIreport on a cell or CSI process with a low BLER, a strictservice/latency requirement, a short TTI length, a large subcarrierspacing, and/or a short processing time is prioritized and updatedfirst. The above operation may be applied such that when multiple CSIreports have the same triggering time or when the triggering time of aCSI report with a high priority is later than that of a CSI report witha low priority, the CSI report with the high priority is updated first.In addition, the operation may be applied such that when multiple CSIreports have the same reporting time or when the reporting time of a CSIreport with a high priority is later than that of a CSI report with alow priority, the CSI report with the high priority is updated first.

UE Capability on Maximum CSI Processes

Currently, UE capability signaling for indicating the maximum number ofCSI processes supportable by the UE configured with transmission mode(TM) 10 has been defined for each component carrier of a specific band.When faster CSI reporting corresponding to sTTI operation is applied,the processing time from CSI measurement to CSI reporting may bedifferent from that of the conventional 1 ms-TTI operation. Thus, it maybe regulated that when the UE configured with TM 10 intends to reportits capability i.e., the maximum number of CSI processes supportable bythe UE for each component carrier of the specific band, the UE reportsthe maximum number of CSI processes independently for each target BLER,service type, numerology, TTI length, combination of DL and UL TTIlengths, and/or processing time or for each combination thereof. Inaddition, the UE capability signaling may be reported independently perband or per band combination.

When the network or eNB configures CSI processes for correspondingcomponent carriers of a corresponding band, the network or eNB mayrecognize the maximum number of configurable CSI processes for the 1 msTTI and/or sTTI and then configure the CSI processes based thereon.

CSI Feedback when TM is Changed Depending on Subframe Types (MBSFN orNon-MBSFN)

It has been considered that a TTI shorter than a subframe is supported.With the introduction of such a sTTI, a method of changing the TM of aPDSCH transmitted in the sTTI in a subframe depending on subframe typeshas also been discussed. For example, a method of configuring aDMRS-based TM for an MBSFN subframe, which is different from the TMconfigured for a non-MBSFN subframe, is under discussion. The presentdisclosure proposes the following CSI feedback methods on the assumptionthat the above operation is supported.

According to the current LTE standards, a CSI reporting mode may bedetermined based on the TM configured for the UE. In particular, whenthe DMRS-based TM, which is different from the TM configured for thenon-MBSFN subframe, is independently configured for the MBSFN subframe,it may be regulated that CSI reporting modes are configured for thecorresponding TMs, respectively. In this case, the CSI reporting modemay be determined according to the following methods.

(Method 1) It may be regulated that a CSI reporting mode correspondingto a TM determined depending on the type (MBSFN or non-MBSFN) of asubframe including a sTTI in which UL grant DCI for triggering CSI istransmitted is used in reporting the corresponding CSI.

(Method 2) It may be regulated that a CSI reporting mode correspondingto a TM determined depending on the type of a subframe including a sTTIfor reporting CSI is used in reporting the corresponding CSI.

(Method 3) It may be regulated that a CSI reporting mode correspondingto the TM configured for the non-MBSFN subframe or a default TM isalways used.

(Method 4) When aperiodic CSI is triggered, the CSI reporting mode maybe explicitly indicated. Alternatively, it may be regulated that a CSIreporting mode implicitly associated with each state indicated by CSIrequest bits is used in reporting the corresponding CSI.

When the DMRS-based TM, which is different from the TM configured forthe non-MBSFN subframe, is independently configured for the MBSFNsubframe, if the sTTI for transmitting the UL grant DCI for triggeringthe CSI and the sTTI for reporting the CSI belong to different types ofsubframes (MBSFN or non-MBSFN), a CSI reference resource may bedetermined except a sTTI having a TM different from that when the CSI isreported.

Aperiodic CSI without UL-SCH for URLLC

According to the current LTE standards, when the conditions described in[Reference] are satisfied, the UE may provide only aperiodic CSIfeedback that is triggered with no transport block (TB) for the UL-SCH.For convenience of description, transmitting UCI with no UL-SCH over thePUSCH is referred to as UCI only PUSCH feedback.

[Reference] Conditions for aperiodic CSI reporting with no UL-SCH

“When DCI format 0 is used and I_MCS=29 or when DCI format 4 is used,only one TB is enabled, I_MCS=29 in the corresponding TB, and the numberof transmission layers is 1,

If the CSI request bit field is one bit, aperiodic CSI reporting istriggered, and N_PRB is less than or equal to 4,

If the CSI request bit filed is two bits, aperiodic CSI reporting istriggered for one serving cell, N_PRB is less than or equal to 4,

If the CSI request bit filed is two bits, aperiodic CSI reporting istriggered for multiple serving cells, N_PRB is less than or equal to 20,

If the CSI request bit filed is two bits, aperiodic CSI reporting istriggered for one CSI process, N_PRB is less than or equal to 4, or

If the CSI request bit filed is two bits, aperiodic CSI reporting istriggered for multiple CSI processes, N_PRB is less than or equal to20,”

If time repetition is applied to PUSCH transmission, the conditions fortriggering CSI reporting on the PUSCH with no UL-SCH need to be changed.Specifically, it may be regulated that the conditions for triggering theCSI reporting on the PUSCH with no UL-SCH are determined by consideringthe MCS index and/or the number of repetitions applied to thecorresponding PUSCH besides N_PRB. For example, when the number of PUSCHrepetitions is set to 2 and then indicated to the UE, it may beregulated that the UE needs to recognize “upper limit value ofN_PRB*repetition number” in the conditions for triggering the CSIreporting on the PUSCH with no UL-SCH as the upper limit value of newN_PRB and then determine whether the CSI reporting on the PUSCH with noUL-SCH is triggered based thereon.

UCI Feedback with Time Repetition

To improve the reliability of UL channel transmission, the timerepetition may be considered. In this case, it is expected that the timerepetition may also increase the reliability of UCI feedback, which istransmitted together with the UL channel. However, if the timerepetition is applied to the UCI feedback as many times as the number oftimes that the PUSCH carrying the UCI feedback is repeated, it may beinefficient in terms of latency. Therefore, the present disclosurepropose the following options. Here, UCI may include not only CSI butalso HARQ-ACK, SR, etc.

Option 1: The time repetition may be applied to the UCI feedback as manytimes as the time repetition number of the PUSCH.

Option 2: The time repetition may be applied to the UCI feedback fewertimes than the time repetition number of the PUSCH. In this case, thetime repetition number of the UCI feedback may be predefinedindependently of the time repetition number of the PUSCH, configured bythe higher layer signal, or indicated by the physical layer signal. Inaddition, information indicating which PUSCH among PUSCHs to which thetime repetition is applied is included and transmitted in the UCIfeedback may be predefined, configured by the higher layer signal, orindicated by the physical layer signal. Moreover, the UCI may be mappedto the same number of REs in every repetition. In this case, the UCImapping order may be determined such that all the repetitions aredistributed in the time domain.

As another method, the number of REs to which the UCI is mapped may varyin each repetition. For example, the number of REs to which the UCI ismapped may be determined such that if the number of REs exceeds acertain level, increasing from the first repetition, the UCI is mappedto the next repetition (or subframe/TTI).

According to the LTE standards, when the UCI is transmitted on thePUSCH, the number of coded symbols (i.e., REs in the LTE standards) forcorresponding UCI transmission is calculated. In particular, when theCSI is transmitted over the PUSCH, the calculation may be performed asfollows.

[Reference 1]

For channel quality control information (CQI and/or PMI denoted asCQI/PMI);

When the UE transmits channel quality control information bits, it shalldetermine the number of modulation coded symbols per layer Q′ forchannel quality information as

$Q^{\prime} = {\min\left( {\left\lceil \frac{\left( {O + L} \right) \cdot M_{sc}^{{PUSCH} - {{initial}(x)}} \cdot N_{symb}^{{PUSCH} - {{initial}(x)}} \cdot \beta_{offset}^{PUSCH}}{\sum\limits_{r = 0}^{C^{(x)} - 1}K_{r}^{(x)}} \right\rceil,{{M_{sc}^{PUSCH} \cdot N_{symb}^{PUSCH}} - \frac{Q_{RI}^{(x)}}{Q_{m}^{(x)}}}} \right)}$

where

-   -   O is the number of CQI/PMI bits, and    -   L is the number of CRC bits given by

$L = \left\{ {\begin{matrix}0 & {O \leq 11} \\8 & {otherwise}\end{matrix},} \right.$

-   -    and

[Reference 2]

Q_(CQI)=Q_(m) ^((x))·Q′ and β_(offset) ^(PUSCH)=β_(offset) ^(CQI), whereβ_(offset) ^(CQI) shall be determined according to [3] depending on thenumber of transmission codewords for the corresponding PUSCH, theduration of the corresponding PUSCH, and on the uplink power controlsubframe set for the corresponding PUSCH when two uplink power controlsubframe sets are configured by higher layers for the cell.

-   -   If neither RI nor CRI is not transmitted then Q_(RI) ^((x))=0.

That is, when the number of coded symbols (or REs) for UCI transmissionin each repetition is calculated under the application of the PUSCH timerepetition, the following issues may be considered for the beta offset(β_(offset) ^(PUSCH)=β_(offset) ^(CQI)).

Option 3: When the time repetition is applied to the PUSCH, it may beregulated that the UCI feedback is transmitted using a large number ofREs in the TTI for one PUSCH (or some PUSCHs) among repeatedlytransmitted PUSCHs by applying a beta offset value higher than thepreviously configured/indicated value. In this case, it may be regulatedthat the UCI feedback is transmitted using a large number of REs in theTTI for one PUSCH (or some PUSCHs) among repeatedly transmitted PUSCHs.The beta offset value may be independent (changed) for each timerepetition number (group). In addition, the beta offset value may beconfigured by the higher layer signal or indicated by the physical layersignal. As another method, the number of coded symbols or REs for thePUSCH may be determined by multiplying the PUSCH repetition number withthe previously configured or indicated beta offset value.

Option 4: When the time repetition is applied to the PUSCH, it may bepredefined, configured by the higher layer signal, or indicated by thephysical layer signal whether the time repetition is applied to the UCIfeedback or whether a large number of REs are used in the TTI for onePUSCH (or some PUSCHs) by applying a high beta offset value.

CQI Table for Different Requirements

In a legacy communication system, a CQI report is calculated based on aBLER requirement of 10{circumflex over ( )}−1. To support a differentrequirement (e.g., a BLER lower than 10{circumflex over ( )}−1) from thelegacy BLER requirement, a new CQI deriving method may be needed. Forexample, when there is any channel requiring a BLER lower than10{circumflex over ( )}−1, a CQI table related to the channel may bedifferent from a CQI table having a BLER requirement of 10{circumflexover ( )}−1.

Each channel may have a channel-specific requirement. The requirementmay be related to one or more of a service type, quality of service(QoS), a target BLER, transmission reliability, a transmission latency,a TTI length, a numerology, and a processing time. One or morerequirements may be considered or configured for a specific channel.When a UE or an eNB is configured with a plurality of channels, each ofthe channels may have a different requirement.

A CQI table may be defined separately for each of other requirements aswell as a BLER requirement. Alternatively, one or more requirements maybe grouped and a CQI table may be defined for each group. A differentCQI table may be laid out according to the type of a requirement or thetype of a group of requirements. Further, as described before inrelation to a BLER, a CQI table may be laid out differently according tohow strict a requirement is. Now, a detailed description will be givenof a CQI table from which a UE is to derive a CQI report.

In consideration of one or more of a CSI link configuration, a CSImeasurement configuration, and a CSI reporting configuration, a CQItable may be configured for each of the configurations for a UE. Forexample, one or more of the CSI link configuration, the CSI measurementconfiguration, and the CSI reporting configuration may be configured foreach of the afore-described requirements. CQI tables may then bedetermined, for mapping to the configured one or more of the CSI linkconfiguration, the CSI measurement configuration, and the CSI reportingconfiguration. For example, when CSI is reported respectively for URLLCand eMBB, a CQI table for URLLC may be determined differently from a CQItable for eMBB.

Alternatively, one or more CQI tables may be configured UE-specificallyfor the UE. The UE may be configured with a CQI table, CQI table 2 inaddition to a default CQI table, CQI table 1, and transmit both ofinformation about a CQI index in the default CQI table and a CQI indexin the additional CQI table, at each CSI feedback. For example, when CQIindex a is derived from CQI table 1 and CQI index b is derived from CQItable 2, the UE may transmit CQI index a and CQI index b as a CSIfeedback to the network. Instead of transmitting CQI index b itself, theUE may represent CQI index b by an offset (a CQI offset) from CQI indexa or information corresponding to the offset and transmit the offset orthe information. This may be similar to increasing delta values Atogether for different CQI tables at all times in calculating/reportingCSI for a wideband/subband.

Alternatively, the UE may transmit information about a CQI table to beused by the UE in UCI. When transmitting a CSI feedback (in which a CQImay be included), the UE may select a value indicating the CQI table andtransmit the selected value. The value indicating the CQI table may betransmitted along with the CQI. Alternatively, the value indicating theCQI table may be transmitted separately from the CQI in a longer timeunit than that of the CQI.

Alternatively, one or more of a different DCI format and/or a differentsearch space may be defined for each requirement. When requirements aregrouped, one or more of a different DCI format and/or a different searchspace may be defined for each group of requirements. A CQI table to beused by the UE may be determined based on the DCI format and/or searchspace of a received control channel.

Alternatively, a different RNTI may be assigned to the UE, for eachrequirement. When requirements are grouped, a different RNTI may beassigned to the UE, for each group of requirements. The UE may identifyan RNTI by which the CRC of a received channel has been masked anddetermine a CQI table to be used based on the RNTI.

Alternatively, each requirement may be linked to a CQI request bit. Whenrequirements are grouped, a CSI request bit may be linked to each groupof requirements. The UE may determine a CQI table to be used based on areceived CSI request bit.

Alternatively, there may be a difference between the number of bits(e.g., X bits) in the CRC of a control channel that triggers a CSItransmission or schedules a channel for the CSI transmission and thenumber of bits in a UE ID (e.g., a Y-bit RNTI). When the number of bitsin the UE ID is less than the number of the CRC bits (e.g., X>Y), all ora part of as many bits as the difference (X-Y) may be used to indicate aCQI table to be used by the UE. Alternatively, all or a part of as manybits as the difference may be used to indicate a CQI offset. All or apart of as many bits as the difference may be used to indicate both ofthe CQI offset and the CQI table to be used by the UE.

A similar operation may be performed in reporting a PMI and an RI aswell as a CQI. For each requirement, a PMI may be calculated separately.The calculated PMIs may be reported together or in the form of PMIoffsets. For each requirement, an RI may be calculated separately. Thecalculated RIs may be reported together or in the form of RI offsets.

CSI Reference Resources for Different Requirements

The UE may receive PDSCHs for different time durations. A schedulingunit for one or more PDSCHs configured/indicated by control informationmay be a slot, a mini-slot, or a plurality of slots. The time durationof data reception may start in the first symbol or any other specificsymbol of a slot within a transmission unit. Because the time durationof data reception may vary, there may be a need for defining the timeduration and overhead of an RS that the UE will assume in calculating aCQI.

In CQI calculation, a CSI reference resource may vary according to thescheduling unit and/or time duration of a PDSCH. Each scheduling unitand/or time duration may be linked to a CQI table. Considering that thescheduling unit and/or time duration of data is not fixed, the UE may bepreconfigured with or receive, by higher-layer signaling, informationabout the starting symbol, ending symbol, time duration (e.g., insymbols, mini-slots, or slots), and/or rate-matching pattern of an RS.

Alternatively, for each CQI table, a CQI reference resource may beconfigured/indicated UE-specifically.

Alternatively, a CSI reference resource to be assumed by the UE may bedefined based on a DCI format and/or a search space. As describedbefore, one or more of a different DCI format and/or a different searchspace may be defined for each requirement. When requirements aregrouped, one or more of a different DCI format and/or a different searchspace may be defined for each group of requirements. A CQI table to beassumed by the UE may vary according to the DCI format and/or searchspace of a received control channel.

Alternatively, a different CSI reference resource may bedetermined/defined for each requirement. When requirements are grouped,a different CSI reference resource may be determined/defined for eachgroup of requirements. For example, given a target BLER of 10%, it maybe determined/defined that the CSI reference resource is located in aTTI earlier than a CSI reporting time by n_{CQI_ref} TTIs or at the timeof a valid TTI which is closest to the TTI earlier than the CSIreporting time by n_{CQI_ref} TTIs before the TTI earlier than the CSIreporting time by n_{CQI_ref} TTIs. When a target BLER is 0.001%, it maybe determined/defined that the CSI reference resource is located in aTTI earlier than a CSI reporting time by k TTIs or at the time of avalid TTI which is closest to the TTI earlier than the CSI reportingtime by k TTIs before the TTI earlier than the CSI reporting time by kTTIs, where k is a value less than n_{CQI_ref}, preconfigured for the UEor received via a physical layer or a higher layer by the UE. The UE mayreport CSI reflecting the latest CSI measurement result, for a stricterBLER requirement.

There may be a need for defining a timing at which a CSI-RS isdetermined to be located. The difference between a CSI feedback time anda time at which a CSI reference resource is located may be derived inconsideration of the following.

A plurality of timing sets may be preconfigured for the UE and whichtiming set to be used may be indicated dynamically to the UE. Forexample, a first timing set may be defined as one of a valid TTI, slot,mini-slot, and symbols which are located before a time earlier than theCSI feedback time by X symbols and closest to the time earlier than theCSI feedback time by X symbols. A second timing set may be defined asone of a valid TTI, slot, mini-slot, and symbols which are locatedbefore a time earlier than the CSI feedback time by X slots and closestto the time earlier than the CSI feedback time by X slots. A valid TTI,slot, mini-slot, or symbols may refer to a TTI, slot, mini-slot, orsymbols including a CSI-RS (or any other RS in which the UE is tomeasure CSI). The first timing set may be used for non-slot-basedscheduling, and the second timing set may be used for slot-basedscheduling. Alternatively, each requirement may be linked to a specifictiming set. When requirements are grouped, each group of requirementsmay be linked to a specific timing set. Information about the linkagemay be preconfigured for the UE or indicated to the UE by physical-layersignaling or higher-layer signaling. In aperiodic CSI reporting,information about a timing set may be linked to an RRC configurationand/or a DCI indication. In aperiodic CSI reporting, an RRCconfiguration and/or a DCI indication may indicate a timing set.

Alternatively, a CSI reference resource may be a slot, a mini-slot, orsymbols including DCI that triggers a CSI transmission. The CSIreference resource may be a plurality of symbols a predetermined timeafter the DCI that triggers the CSI transmission. Information about thepredetermined time may be predefined for the UE or indicated to the UEby physical-layer signaling or higher-layer signaling.

MCSs/TBSs for Different Requirements

To support different requirements, a plurality of MCS tables may beconfigured for the UE. Which one of the MCS tables the UE is to use maybe indicated.

A different MCS table may be configured according to a PDSCH mappingtype. Because PDSCH mapping type B may also serve a usage other thanURLLC, an MCS table may be indicated by a time domain resourceallocation field. Information indicating an MCS table to be used may beadded in an entry of an indication table of the time domain resourceallocation field. The information indicating an MCS table to be used maybe used to identify an MCS table for a target BLER. Informationindicating a different MCS table depending on whether 256-ary quadratureamplitude modulation (256QAM) is used and/or pi/2-binary phase shiftkeying (BPSK) is used may be transmitted UE-specifically by higher-layersignaling. For example, information indicating a QAM related to an MCStable to be used by the UE may include information indicating that theUE is to use an MCS table related to 256QAM or information indicatingthat the UE is to use an MCS table related to 64QAM or less. In anotherexample, the MCS table related to 256QAM may be used only when the timedomain resource allocation field indicates use of an eMBB table.

Alternatively, it may be regulated that a different MCS table is usedaccording to the periodicity of a search space. An MCS table may beconfigured according to the periodicity of a search space by a searchspace configuration. For example, a default MCS table may be used for aspecific search space. In a specific example, an MCS table for eMBBand/or BLER=10% may be used for a common search space and/or a searchspace for a remaining minimum system information CORESET (RMSI CORESET)(i.e., a CORESET configured by a PBCH).

Alternatively, it may be regulated that a different MCS table is usedfor each DCI format.

Alternatively, a different MCS table may be defined according to thescheduling unit and/or scheduling time duration of data. An MCS tablemay be preconfigured implicitly for each scheduling unit and/or eachscheduling time duration of data. Alternatively, the indication tableincluded in the time domain resource allocation field may include a rowwith an indication indicating which MCS table is to be used. When thenumber of bits in the time domain resource allocation field is equal toor less than a specific value, it may be regulated that an MCS table forURLLC is used. For example, when DCI-based time domain resourceallocation (RA) is not performed, an MCS table for URLLC may be used forthe UE. The UE may assume that allocated time domain resources are notflexible in URLLC.

Alternatively, sets of MCS values may be predefined. The sets of MCSvalues may be configured for the UE by physical-layer signaling orhigher-layer signaling. Alternatively, a plurality of MCS tables may bedefined in the form of a single MCS table. The plurality of MCS tablesmay include common MCS entries. An MCS offset may be indicated by DCI.To indicate the MCS offset, a separate field may be configured in theDCI, or the DCI may be linked to the time domain allocation field. TheUE may select an MCS by taking an MCS field and an MCS offset incombination. The UE may select an MCS by taking DCI field values incombination. A newly defined MCS may merely include some states inaddition to an existing MCS. The added states may be related to a lowestMCS. When a new MCS is defined just by adding some states an existingMCS, the MCS may be represented by a combination of DCI field values(e.g., RA set to full). For example, an MCS table may include N entriesin total, ranging from entry (or index) 0 to entry (index) N−1.Basically, the UE may be configured to use M MCS entries from N−M−1(M<N) to N−1. Additionally, despite a default configuration, the UE maybe configured to use entries 0 to M−1 or offset value to M+offsetvalue−1 according to an offset represented by a combination of specificfields. The UE may derive the offset by interpreting the combination ofthe specific fields.

Alternatively, a different RNTI may be assigned to the UE, for eachrequirement. When requirements are grouped, a different RNTI may beassigned to the UE, for each group of requirements. The requirements mayinclude one or more of a reliability requirement, a latency requirement,a target BLER, a service type, a TTI length, a numerology, and aprocessing time, as described before. The UE may identify an RNTIrelated to a received channel and determine an MCS table to be used,based on the identified RNTI.

For example, the UE may be configured with a plurality of MCS tables byhigher-layer signaling (e.g., RRC signaling). Alternatively, theplurality of MCS tables may be predefined for the UE.

As described before, a PDCCH may be used to schedule a PUSCH or a PDSCH.An RNTI by which a PDCCH for scheduling a data channel is masked and/orCRC-scrambled may be determined based on a channel-specific requirement.For example, a PDCCH that schedules a specific channel may be CRC-maskedand/or scrambled with a different RNTI according to a BLER required forthe specific channel. Different RNTIs may be determined for a channelwith a BLER of 10% and a channel with a BLER of 0.0001%. The eNB mayconfigure different RNTIs for use in CRC scrambling of a PDCCH forscheduling a channel with a BLER of 10% and a PDCCH for scheduling achannel with a BLER of 0.0001%. An RNTI defined in the legacy system maybe used. Alternatively, an RNTI may be newly defined for configuring anMCS table. The newly defined RNTI may be referred to as an MCS-cell-RNTI(MCS-C-RNTI). The eNB may configure the defined RNTI for a specific UEand assign the RNTI to the specific UE. The UE may be configured withthe RNTI received from the eNB.

The UE may receive a PDCCH that schedules a PDSCH or a PUSCH. The UEidentifies an RNTI by which the PDCCH has been CRC-masked and/orCRC-scrambled.

An MCS table corresponding to the RNTI identified by the UE may havebeen configured. The UE may determine an MCS table for use in receivinga PDSCH scheduled by the PDCCH or transmitting a PUSCH scheduled by thePDCCH, based on the identified RNTI. The BLER of a channel scheduled bya PDCCH with a CRC scrambled by the MCS-C-RNTI may be different from theBLER of a channel scheduled by a PDCCH with a CRC scrambled by anotherRNTI. Accordingly, the two channels with different BLERs may usedifferent MCS tables. Whether the newly defined RNTI related to an MCStable has been configured for the UE or an RNTI related to a specificchannel has been configured for the UE may further be considered.

When a received PDCCH is CRC-scrambled with the MCS-C-RNTI, the UE maybe configured to use a first MCS table and otherwise, a second MCStable. Alternatively, when the received PDCCH is CRC-scrambled with theMCS-C-RNTI, the UE may be configured to use the first MCS table. Whenthe received PDCCH is CRC-scrambled with a cell-RNTI (C-RNTI) orconfigured scheduling-RNTI (CS-RNTI), the UE may be configured to usethe second MCS table. Otherwise, the UE may be configured to use a thirdMCS table. Alternatively, an additional condition (e.g., informationindicating a QAM related to an MCS table to be used by the UE, a DCIformat, and/or repeated transmission or non-repeated transmission andthe type of a repeated transmission configuration of a PDSCH (or PUSCH))may further be considered. Even for one RNTI, the UE may be configuredto use the first MCS table when an additional first condition issatisfied, and the second MCS table when an additional second conditionis satisfied. Alternatively, when a received PDCCH is CRC-scrambled withthe MCS-C-RNTI, the UE may be configured to use the first MCS table.When the received PDCCH is CRC-scrambled with the CS-RNTI and theadditional first condition is satisfied, the UE may be configured to usethe second MCS table. When the received PDCCH is CRC-scrambled with theCS-RNTI and the additional second condition is satisfied, the UE may beconfigured to use the first MCS table.

Table 13 to Table 17 are exemplary MCS tables available to the UE.

TABLE 13 MCS Index Modulation Target code Spectral I_(MCS) Order Q_(m)Rate R x [1024] efficiency  0 2 120 0.2344  1 2 157 0.3066  2 2 1930.3770  3 2 251 0.4902  4 2 308 0.6016  5 2 379 0.7402  6 2 449 0.8770 7 2 526 1.0273  8 3 602 1.1758  9 2 679 1.3262 10 4 340 1.3281 11 4 3781.4766 12 4 434 1.6953 13 4 490 1.9141 14 4 553 2.1602 15 4 616 2.406316 4 658 2.5703 17 6 438 2.5664 18 6 466 2.7305 19 6 517 3.0293 20 6 5673.3223 21 6 616 3.6094 22 6 666 3.9023 23 6 719 4.2129 24 6 772 4.523425 6 822 4.8164 26 6 873 5.1152 27 6 910 5.3320 28 6 948 5.5547 29 2reserved 30 4 reserved 31 6 reserved

TABLE 14 MCS Index Modulation Target code Spectral I_(MCS) Order Q_(m)Rate R x [1024] efficiency  0 2 120 0.2344  1 2 193 0.3770  2 2 3030.6016  3 2 449 0.8770  4 2 602 1.1758  5 4 378 1.4766  6 4 434 1.6953 7 4 490 1.9141  8 4 553 2.1602  9 4 616 2.4063 10 4 658 2.5703 11 6 4662.7305 12 6 517 3.0293 13 6 567 3.3223 14 6 616 3.6094 15 6 666 3.902316 6 719 4.2129 17 6 772 4.5234 18 6 822 4.8164 19 6 873 5.1152 20 8682.5 5.3320 21 8 711 5.5547 22 8 754 5.8906 23 8 797 6.2266 24 8 8416.5703 25 8 885 6.9141 26 8 916.5 7.1602 27 8 948 7.4063 28 2 reserved29 4 reserved 30 6 reserved 31 8 reserved

TABLE 15 MCS Index Modulation Target code Spectral I_(MCS) Order Q_(m)Rate R x [1024] efficiency  0 2 38 0.0586  1 2 40 0.0781  2 2 50 0.0977 3 2 64 0.1250  4 2 78 0.1523  5 2 99 0.1934  6 2 120 0.2344  7 2 1570.3066  8 2 193 0.3770  9 2 251 0.4902 10 2 308 0.6016 11 2 379 0.740212 2 449 0.8770 13 2 526 1.0273 14 2 602 1.1758 15 4 340 1.3281 18 4 3781.4766 17 4 434 1.6953 18 4 490 1.9141 19 4 553 2.1602 20 4 616 2.406321 6 438 2.5664 22 6 466 2.7305 23 6 517 3.0293 24 6 567 3.3223 25 6 6163.6094 26 6 666 3.9023 27 6 719 4.2129 28 6 772 4.5234 28 2 reserved 304 reserved 31 6 reserved

TABLE 16 MCS Index Modulation Target code Spectral I_(MCS) Order Q_(m)Rate R x 1024 efficiency  0 q 240/q 0.2344  1 q 314/q 0.3066  2 2 1930.3770  3 2 251 0.4902  4 2 308 0.6016  5 2 379 0.7402  6 2 449 0.8770 7 2 526 1.0273  8 2 602 1.1758  9 2 679 1.3262 10 4 340 1.3281 11 4 3781.4766 12 4 434 1.6953 13 4 490 1.9141 14 4 553 2.1602 15 4 616 2.406316 4 658 2.5703 17 6 466 2.7305 18 6 517 3.0293 19 6 567 3.3223 26 6 6163.6094 21 6 666 3.9023 22 6 719 4.2129 23 6 772 4.5234 24 6 822 4.816425 6 873 5.1152 26 6 910 5.3320 27 6 948 5.5547 28 q reserved 29 2reserved 30 4 reserved 31 6 reserved

TABLE 17 MCS Index Modulation Target code Spectral I_(MCS) Order Q_(m)Rate R x 1024 efficiency  0 q  60/q 0.0586  1 q  80/q 0.0781  2 q 100/q0.0977  3 q 128/q 0.1250  4 q 156/q 0.1523  5 q 198/q 0.1934  6 2 1200.2344  7 2 157 0.3066  8 2 193 0.3770  9 2 251 0.4902 10 2 308 0.601611 2 379 0.7402 12 2 449 0.8770 13 2 526 1.0273 14 2 602 1.1758 15 2 6791.3262 16 4 378 1.4766 17 4 434 1.6953 18 4 490 1.9141 19 4 553 2.160226 4 616 2.4063 21 4 658 2.5703 22 4 699 2.7305 23 4 772 3.0156 24 6 5673.3223 25 6 616 3.6094 26 6 666 3.9023 27 6 772 4.5234 28 q reserved 292 reserved 30 4 reserved 31 6 reserved

The UE may use an MCS field I_(mcs) included in DCI received on a PDCCHand a determined MCS table to determine a modulation order Q_(m) and atarget code rate R for PDSCH reception or PUSCH transmission. The UE mayselect an MCS index indicated by the MCS field in the determined MCStable. The UE may decode and/demodulate a PDSCH based on the selectedMCS index. The UE may encode and/or modulate a PUSCH based on theselected MCS index.

Alternatively, there may be a difference between the number of bits(e.g., X bits) in the CRC of a control channel for data channelscheduling and the number of bits in a UE ID (e.g., a Y-bit RNTI). Whenthe number of bits in the UE ID is less than the number of the CRC bits(e.g., X>Y), all or a part of as many bits as the difference (X-Y) maybe used to indicate an MCS table to be used by the UE. Alternatively,all or a part of as many bits as the difference may be used to indicatean MCS offset. All or a part of as many bits as the difference may beused to indicate both of the CQI table to be used by the UE and the CQIoffset.

CSI Reporting for Different Requirements

CSI may be reported on one channel based on CSI reference resources fordifferent requirements. For example, a different target BLER may be setfor each CSI process, and the UE may report CSI for a plurality of CSIprocesses having different target BLERs on one channel.

When CSI is reported on one channel, it may be determined differentlywhether the CSI is to be reported according to the requirement of thechannel carrying the CSI report. For example, when CSI is reported on aPUSCH having a target BLER of 0.001%, the UE may report only CSI for aCSI process having the target BLER of 0.001%. When CSI is reported on aPUSCH having a target BLER of 10%, the UE may report CSI for alltriggered CSI processes. The UE may include CSI for a CSI process havinga less strict requirement than a channel carrying a CSI report, in thechannel.

Alternatively, a channel carrying a CSI report may be determineddifferently according to the requirement of a CSI process. For example,a CSI report for a CSI process having a target BLER of 0.001% may betransmitted on a PUSCH having the target BLER of 0.001%. A CSI reportfor a CSI process having a target BLER of 10% may be transmitted on aPUSCH having the target BLER of 10%. Even though a CSI report for a CSIprocess having the target BLER of 10% is scheduled on a PUSCH having thetarget BLER of 0.001%, the CSI report may be transmitted on a channel ina cell/TTI different from that of the scheduled PUSCH. When CSI (a CSIprocess) for a CSI reference resource having a specific requirement maynot be included even in a channel transmitted in another cell/TTI, itmay be regulated that the CSI (CSI process) is dropped.

Alternatively, it may be configured that a channel carrying a CSI reportis repeatedly transmitted (time repetition in which the same resourceblock is repeatedly transmitted in a plurality of TTIs). For each CSIreference resource having a requirement, it may be determined whether totransmit CSI (a CSI process) for the CSI reference resource on a channelwhich is being repeatedly transmitted. The CSI (CSI process) may also betransmitted repeatedly at each repeated transmission of the channel. TheCSI (CSI process) may be transmitted repeatedly only a predeterminednumber of times, together with the repeatedly transmitted channel. Forexample, a CSI report for a CSI process having a target BLER of 0.001%is transmitted together repeatedly at each transmission of a repeatedlytransmitted channel, and a CSI report for a CSI process having a targetBLER of 10% is transmitted only at the first transmission (or a specificindicated/configured transmission) of a repeatedly transmitted channel.

Semi-Persistent Scheduling (SPS) with Different Requirements

In SPS, the periodicity of repeated transmission of a data channel isconfigured for the UE by higher-layer signaling. The UE may transmit andreceive the data channel even without DCI for resource configurationuntil before an SPS configuration is released. Because there is no DCIfor scheduling the resources of each of repeatedly transmitted datachannels, a method of indicating the requirement of a data channel to aUE may be proposed.

A different SPS resource may be configured for each requirement. Alongwith an SPS configuration, a requirement for the SPS configuration mayalso be configured. When a data channel is transmitted in apredetermined resource (or periodically) without scheduling DCI, thesame thing may be applied even without an SPS configuration.

Data channels transmitted according to a plurality of SPS configurationsmay overlap with each other over a specific time period. When datachannels are overlapped with each other over a predetermined timeperiod, data channels to be transmitted may be determined according tothe priorities of requirements for the SPS configurations. For example,a data channel related to an SPS configuration set to higherreliability, a lower latency, a lower BLER, a shorter TTI length, alarger SCS, or a shorter processing time may be transmitted, while adata channel related to an SPS configuration with a relatively lowpriority may be dropped.

Alternatively, one or more of the transmission reliability, latency,target BLER, and service type requirements of an SPS transmission may belinked to one or more of a TTI length, a numerology, a processing time,and a transmission periodicity. Once one or more of the TTI length,numerology, processing time, and transmission periodicity of anSPS-based data channel are configured, one or more of the transmissionreliability, latency, target BLER, and service type requirements of theSPS-based data channel may be determined implicitly.

Alternatively, information about one or more requirements may betransmitted in a physical signal (L1 signaling, for example, on a PDCCH)for activating SPS. The information about one or more requirements maybe represented by combining specific states of specific fields (or oneor more newly defined fields) in the L1 signaling for activatingtransmission of an SPS-based data channel.

CSI Update/Calculation-Related Capability for sTTI

The UE may report its UE capability to the network. The UE capabilitymay include a maximum simultaneous CSI update/calculation capability ofthe UE. In an sTTI-related operation, a processing time may varyaccording to a DL and UL TTI length combination, thus leading to adifferent simultaneous CSI update/calculation capability of the UE. Forexample, in an sTTI-related operation, a PDSCH reception to HARQ-ACKtransmission timing gap and/or a UL grant reception to PUSCHtransmission timing gap may vary according to a combination of DL and ULTTI lengths. The UE combines one or more of a DL and UL TTI lengthcombination, a processing time, a maximum timing advance (TA) value, ashort PDCCH (sPDCCH) RS type, and the number of sPDCCH symbols, andreports its simultaneous CSI update/calculation capability for eachcombination to the network. The CSI update/calculation capability may bereported on a cell basis and/or on a CSI process basis. The UE maycombine one or more of the DL and UL TTI length combination, theprocessing time, the maximum TA value, the sPDCCH RS type, and thenumber of sPDCCH symbols, and report its capability on a maximum numberof simultaneous CSI reports for each combination to the network. The UEmay transmit the capability report on a frequency band basis. The UE maytransmit the capability report on a frequency band combination basis. Adifferent UE capability reporting rule may be defined for each frequencyband or each frequency band combination. The UE may not be indicated toperform update/calculation for cells and/or CSI processes beyond itsreported CSI update/calculation capability.

For example, the UE may transmit, to the network, information indicatinga maximum number of updatable CSI processes, for each combination of DLand UL TTI lengths. A parameter/indicator may be configured to representthe information indicating the maximum number of updatable CSIprocesses, for each combination of DL and UL TTI lengths. The UE mayalso report information about all or a part of combinations to thenetwork. DL and UL TTI length combinations may be produced as listed inTable 18 below.

TABLE 18 DL UL Slot Slot Subslot Slot Subslot Subslot

A DL and UL combination of {Slot, Slot} may be referred to as Comb77, aDL and UL combination of {Subslot, Slot} may be referred to as Comb27,and a DL and UL combination of {Sublot, Sublot} may be referred to asComb22.

For Comb22, two sets of processing timelines may be configured. Each setmay have different processing timelines in terms of a maximum TA. Forprocessing timeline set 1, a minimum processing timeline may be set ton+4 or n+6, and for processing timeline set 2, a minimum processingtimeline may be set to n+6 or n+8. A range of TA values may be set foreach processing timeline set as listed in Table 19 below.

TABLE 19 Range of N_(TA) proc-Timeline 0 ≤ N_(TA) ≤ 2048 nplus4set1 0 ≤N_(TA) ≤ 10816 nplus6set1 0 ≤ N_(TA) ≤ 5120 nplus6set2 0 ≤ N_(TA) ≤13888 nplus8set2

For each of four combinations produced from Comb77, Comb27, andprocessing timeline set 1 of Comb22 (Comb22-Set1) and processingtimeline set 2 of Comb22 (Comb22-Set2), the UE may transmit informationindicating a maximum number of updatable CSI processes to the network.Four parameters/indicators may be configured to represent theinformation indicating the maximum number of updatable CSI processes foreach of the four combinations. The maximum number of updatable CSIprocesses may be set to range from 1 to 32.

The UE may report its UE capability, upon request of the eNB. Uponreceipt of the request from the eNB, the UE may report fourparameters/indicator for four combinations as its UE capability to thenetwork. The UE may then expect not to receive an indication indicatingCSI process updates beyond its reported UE capability.

FIG. 10 is a conceptual view illustrating a method of transmitting andreceiving a signal according to embodiments of the present disclosure.

Referring to FIG. 10 , the signal transmission and reception methodaccording to embodiments of the present disclosure may includeconfiguring an RNTI related to an MCS (S1001), receiving a controlchannel for scheduling transmission of a UL data channel or reception ofa DL data channel (S1003), and transmitting the UL data channel orreceiving the DL data channel, which has been scheduled by the controlchannel, based on one of a plurality of MCS tables (S1005).

Particularly, the MCS table may be determined based on the RNTI relatedto an MCS and an RNTI related to the control channel. The MCS table maybe determined in further consideration of information indicating a QAMrelated to the MCS table to be used by the UE, received by higher-layersignaling.

The signal transmission and reception method according to embodiments ofthe present disclosure may further include transmitting UE capabilityinformation to a network. The UE capability information may includeinformation about the number of updatable CSI processes for each DL andUL TTI length combination. The information about the number of updatableCSI processes for each DL and UL TTI length combination may include afirst indicator indicating the number of CSI processes for a combinationof slot and slot as the DL and UL TTI length combination, a secondindicator indicating the number of CSI processes for a combination ofsubslot and slot as the DL and UL TTI length combination, a thirdindicator indicating the number of CSI processes for a combination ofsubslot and subslot as the DL and UL TTI length combination and aconfigured first processing time, and a fourth indicator indicating thenumber of CSI processes for a combination of subslot and subslot as theDL and UL TTI length combination and a configured second processingtime. In addition to the above-described operation, one or more of theoperations proposed in the embodiments of the present disclosure may beperformed in combination.

Since each of the examples of the proposed methods may be included asone method for implementing the present disclosure, it is apparent thateach example can be regarded as a proposed method. In addition, althoughthe proposed methods can be implemented independently, some of theproposed methods can be combined (or merged) for implementation.Moreover, a rule may be defined such that information on whether theproposed methods are applied (or information on rules related to theproposed methods) should be transmitted from a BS to a UE through apredefined signal (e.g., a physical layer signal, a higher layer signal,etc.).

Device Configuration

FIG. 11 is a block diagram illustrating a transmitting device 10 and areceiving device 20 configured to implement embodiments of the presentdisclosure. Each of the transmitting device 10 and receiving device 20includes a transmitter/receiver 13, 23 capable of transmitting orreceiving a radio signal that carries information and/or data, a signal,a message, etc., a memory 12, 22 configured to store various kinds ofinformation related to communication with a wireless communicationsystem, and a processor 11, 21 operatively connected to elements such asthe transmitter/receiver 13, 23 and the memory 12, 22 to control thememory 12, 22 and/or the transmitter/receiver 13, 23 to allow the deviceto implement at least one of the embodiments of the present disclosuredescribed above.

The memory 12, 22 may store a program for processing and controlling theprocessor 11, 21, and temporarily store input/output information. Thememory 12, 22 may also be utilized as a buffer. The processor 11, 21controls overall operations of various modules in the transmittingdevice or the receiving device. Particularly, the processor 11, 21 mayperform various control functions for implementation of the presentdisclosure. The processors 11 and 21 may be referred to as controllers,microcontrollers, microprocessors, microcomputers, or the like. Theprocessors 11 and 21 may be achieved by hardware, firmware, software, ora combination thereof. In a hardware configuration for an embodiment ofthe present disclosure, the processor 11, 21 may be provided withapplication specific integrated circuits (ASICs) or digital signalprocessors (DSPs), digital signal processing devices (DSPDs),programmable logic devices (PLDs), and field programmable gate arrays(FPGAs) that are configured to implement the present disclosure. In thecase which the present disclosure is implemented using firmware orsoftware, the firmware or software may be provided with a module, aprocedure, a function, or the like which performs the functions oroperations of the present disclosure. The firmware or softwareconfigured to implement the present disclosure may be provided in theprocessor 11, 21 or stored in the memory 12, 22 to be driven by theprocessor 11, 21.

The processor 11 of the transmitter 10 performs predetermined coding andmodulation of a signal and/or data scheduled by the processor 11 or ascheduler connected to the processor 11, and then transmits a signaland/or data to the transmitter/receiver 13. For example, the processor11 converts a data sequence to be transmitted into K layers throughdemultiplexing and channel coding, scrambling, and modulation. The codeddata sequence is referred to as a codeword, and is equivalent to atransport block which is a data block provided by the MAC layer. Onetransport block is coded as one codeword, and each codeword istransmitted to the receiving device in the form of one or more layers.To perform frequency-up transformation, the transmitter/receiver 13 mayinclude an oscillator. The transmitter/receiver 13 may include Nttransmit antennas (wherein Nt is a positive integer greater than orequal to 1).

The signal processing procedure in the receiving device 20 is configuredas a reverse procedure of the signal processing procedure in thetransmitting device 10. The transmitter/receiver 23 of the receivingdevice 20 receives a radio signal transmitted from the transmittingdevice 10 under control of the processor 21. The transmitter/receiver 23may include Nr receive antennas, and retrieves baseband signals byfrequency down-converting the signals received through the receiveantennas. The transmitter/receiver 23 may include an oscillator toperform frequency down-converting. The processor 21 may perform decodingand demodulation on the radio signal received through the receiveantennas, thereby retrieving data that the transmitting device 10 hasoriginally intended to transmit.

The transmitter/receiver 13, 23 includes one or more antennas. Accordingto an embodiment of the present disclosure, the antennas function totransmit signals processed by the transmitter/receiver 13, 23 are toreceive radio signals and deliver the same to the transmitter/receiver13, 23. The antennas are also called antenna ports. Each antenna maycorrespond to one physical antenna or be configured by a combination oftwo or more physical antenna elements. A signal transmitted through eachantenna cannot be decomposed by the receiving device 20 anymore. Areference signal (RS) transmitted in accordance with a correspondingantenna defines an antenna from the perspective of the receiving device20, enables the receiving device 20 to perform channel estimation on theantenna irrespective of whether the channel is a single radio channelfrom one physical antenna or a composite channel from a plurality ofphysical antenna elements including the antenna. That is, an antenna isdefined such that a channel for delivering a symbol on the antenna isderived from a channel for delivering another symbol on the sameantenna. An transmitter/receiver supporting the Multiple-InputMultiple-Output (MIMO) for transmitting and receiving data using aplurality of antennas may be connected to two or more antennas.

In embodiments of the present disclosure, the UE or the terminaloperates as the transmitting device 10 on UL, and operates as thereceiving device 20 on DL. In embodiments of the present disclosure, theeNB or the base station operates as the receiving device 20 on UL, andoperates as the transmitting device 10 on DL.

The transmitting device and/or receiving device may be implemented byone or more embodiments of the present disclosure among the embodimentsdescribed above.

Detailed descriptions of preferred embodiments of the present disclosurehave been given to allow those skilled in the art to implement andpractice the present disclosure. Although descriptions have been givenof the preferred embodiments of the present disclosure, it will beapparent to those skilled in the art that various modifications andvariations can be made in the present disclosure defined in the appendedclaims. Thus, the present disclosure is not intended to be limited tothe embodiments described herein, but is intended to have the widestscope consistent with the principles and novel features disclosedherein.

As described above, the present disclosure is applicable to variouswireless communication systems.

What is claimed is:
 1. A method of transmitting and receiving a signal,performed by a Base Station (BS) in a wireless communication system, themethod comprising: receiving user equipment (UE) capability informationfrom a UE, wherein the UE capability information includes (i) firstinformation regarding a maximum number of Channel State Information(CSI) processes that can be updated for a first processing time of acombination of downlink/uplink Transmission Time Interval (TTI) lengthand (ii) second information regarding a maximum number of CSI processesthat can be updated for a second processing time of the combination ofdownlink/uplink TTI length, wherein the combination of downlink/uplinkTTI length is subslot/subslot, and wherein the UE capability informationfurther includes (iii) third information regarding a maximum number ofCSI processes that can be updated for a combination of downlink/uplinkTTI length as slot/slot and (iv) fourth information regarding a maximumnumber of CSI processes that can be updated for a combination ofdownlink/uplink TTI length as subslot/slot; and transmitting, to the UE,an update request for one or more CSI processes, wherein a number of theone or more CSI processes is not larger than a number of CSI processesreported by the UE capability information.
 2. The method according toclaim 1, wherein the BS is configured to communicate with at least oneof UEs, a UE related to an autonomous driving vehicle.
 3. A Base Station(BS) for transmitting and receiving a signal in a wireless communicationsystem, the BS comprising: a transceiver; a processor configured tocontrol the transceiver; and a non-transitory computer-readable storagemedium storing instructions that, based on being executed by theprocessor, perform operations comprising: controlling the transceiver toreceive User Equipment (UE) capability information from a UE, whereinthe UE capability information includes (i) first information regarding amaximum number of Channel State Information (CSI) processes that can beupdated based on a first processing time configured for a combination ofdownlink/uplink Transmission Time Interval (TTI) length and (ii) secondinformation regarding a maximum number of CSI processes that can beupdated based on a second processing time configured for the combinationof downlink/uplink TTI length, wherein the combination ofdownlink/uplink TTI length is subslot/subslot, and wherein the UEcapability information further includes (iii) third informationregarding a maximum number of CSI processes that can be updated for acombination of downlink/uplink TTI length as slot/slot and (iv) fourthinformation regarding a maximum number of CSI processes that can beupdated for a combination of downlink/uplink TTI length as subslot/slot;and controlling the transceiver to transmit, to the UE, an updaterequest for one or more CSI processes, wherein a number of the one ormore CSI processes is not larger than a number of CSI processes reportedby the UE capability information.
 4. The BS according to claim 3,wherein the BS is configured to communicate with at least one of UEs, aUE related to an autonomous driving vehicle.
 5. A non-transitorycomputer-readable storage medium storing instructions that, based onbeing executed by a processor, perform operations comprising: receivingUser Equipment (UE) capability information from the UE, wherein the UEcapability information includes (i) first information regarding amaximum number of Channel State Information (CSI) processes that can beupdated based on a first processing time configured for a combination ofdownlink/uplink Transmission Time Interval (TTI) length and (ii) secondinformation regarding a maximum number of CSI processes that can beupdated based on a second processing time configured for the combinationof downlink/uplink TTI length, wherein the combination ofdownlink/uplink TTI length is subslot/subslot, and wherein the UEcapability information further includes (iii) third informationregarding a maximum number of CSI processes that can be updated for acombination of downlink/uplink TTI length as slot/slot and (iv) fourthinformation regarding a maximum number of CSI processes that can beupdated for a combination of downlink/uplink TTI length as subslot/slot;and transmitting, to the UE, an update request for one or more CSIprocesses, wherein a number of the one or more CSI processes is notlarger than a number of CSI processes reported by the UE capabilityinformation.